https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101769
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
free_all2_r loses it during CDDCE1 which elides the original while loop. Then
tail-recursion discovers a new loop from the following IL
void free_all2_r (struct Node * n_)
{
struct Node * t;
struct Node * _1;
<bb 2> :
_1 = n__6(D)->right;
if (_1 != 0B)
goto <bb 3>; [INV]
else
goto <bb 4>; [INV]
<bb 3> :
free_all2_r (_1);
<bb 4> :
return;
which leaves loop fixup to discover the created loop which is then
not marked as finite (I don't think we can technically say it is?):
fix_loop_structure: fixing up loops for function
flow_loops_find: discovered new loop 2 with header 2
that then gets inlined into free_all2. free_all suffers from exactly the
same issue. The info doesn't get lost - it's simply that tail recursion
added loops are not marked finite.
I guess since it's recursion we know it will eventually terminate (blow
the stack). But the tail-recursion pass doesn't bother to create the
loop structure where it could set ->finite_p.
if (changed)
{
/* We may have created new loops. Make them magically appear. */
loops_state_set (LOOPS_NEED_FIXUP);
free_dominance_info (CDI_DOMINATORS);
}
I have a patch that tries to fix that. With this all functions end up empty.
