On 16/03/16 09:53, Richard Biener wrote:
Hmm, it looks like for all what this function does this effectively
pessimizes scop merging and it would be easier to split 'exit'
in case its destination is unsuitable (not trivially empty).
Agreed.
The
/* For now we just want to bail out when exit does not post-dominate
entry.
TODO: We might just add a basic_block at the exit to make exit
post-dominate entry (the entire region). */
if (!dominated_by_p (CDI_POST_DOMINATORS, get_entry_bb (combined),
get_exit_bb (combined))
|| !dominated_by_p (CDI_DOMINATORS, get_exit_bb (combined),
comment also suggests that splitting the get_nearest_pdom_with_single_exit
edge and including the new BB in the combined region would also always fix
the dominance relation (though I don't see how it could do that and
the comment looks wrong and by construction the check should never
trigger).
I've replaced the entire condition with two asserts:
...
diff --git {a,b}/gcc/graphite-scop-detection.c
index 7615842..762a248 100644
--- a/gcc/graphite-scop-detection.c
+++ b/gcc/graphite-scop-detection.c
@@ -820,14 +820,10 @@ scop_detection::merge_sese
/* For now we just want to bail out when exit does not post-dominate
entry.
TODO: We might just add a basic_block at the exit to make exit
post-dominate entry (the entire region). */
- if (!dominated_by_p (CDI_POST_DOMINATORS, get_entry_bb (combined),
- get_exit_bb (combined))
- || !dominated_by_p (CDI_DOMINATORS, get_exit_bb (combined),
- get_entry_bb (combined)))
- {
- DEBUG_PRINT (dp << "[scop-detection-fail] cannot merge "
- "seses.\n");
- return invalid_sese;
- }
+ gcc_assert (dominated_by_p (CDI_POST_DOMINATORS,
+ get_entry_bb (combined),
+ get_exit_bb (combined)));
+ gcc_assert (dominated_by_p (CDI_DOMINATORS,
+ get_exit_bb (combined),
+ get_entry_bb (combined)));
/* FIXME: We should remove this piece of code once
canonicalize_loop_closed_ssa has been removed, because that function
...
and ran graphite.exp.
I ran into an ICE for pr68693.f90, for the second assert. The exit bb
has two incoming edges from within the sese, and one from outside. Given
that the exit bb is empty, we could split the exit edge and redirect the
edge from outside the sese to the new bb, which would fix the sese.
Perhaps that is what is meant in the comment, I'm not sure.
Thanks,
- Tom
