http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46787
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2010-12-03
15:37:16 UTC ---
To fix:
/* FIXME -- data dependence analysis does not work correctly for objects
with invariant addresses in loop nests. Let us fail here until the
problem is fixed. */
if (dr_address_invariant_p (dr) && nest)
{
free_data_ref (dr);
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "\tFAILED as dr address is invariant\n");
ret = false;
break;
}
for this to work and be a real improvement we need to pass down the
minimum iterations of the loop (thus, the minimum vectorization factor
in case of the vectorizer).
We can also fix it up locally in the vectorizer when
compute_data_dependences_for_loop would not re-scan the loop
for data references (but we'd do it in the vectorizer and remove
the scalar loads).
We can also avoid computing data dependences until
vect_analyze_data_ref_dependences then and save some compile-time for
non-vectorized loops.
