http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48955
--- Comment #7 from tkoenig at netcologne dot de <tkoenig at netcologne dot de>
2011-05-16 18:10:03 UTC ---
Hi Paul,
> Indeed - I just need to find the time to sort out the logic.
> Structurally the patch is OK.
I think the logic could be as follows: You could have two flags, one
FORWARD_ALLOWED and one BACKWARD_ALLOWED.
Initialize both flags to true.
Run through all the references which could introduce a dependency.
If there is a GFC_EQUAL dependency, do nothing. If there is a
GFC_FORWARD dependency, set BACKWARD_ALLOW to false. If there
is a GFC_BACKWARD dependency, set FORWARD_ALLOW to false.
When selecting the loop direction:
- If FORWARD_ALLOW is set, select a forward loop; else
If BACKWARD_ALLOW is set, select a forward loop;
else mark this dimension as needing a temporary.
Does this sound OK?
Thomas
