tree-optimization/113026 - fix vector epilogue maximum iter bound
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Commit Message
The late amendment with a limit based on VF was redundant and wrong
for peeled early exits. The following moves the adjustment done
when we don't have a skip edge down to the place where the already
existing VF based max iter check is done and removes the amendment.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
PR tree-optimization/113026
* tree-vect-loop-manip.cc (vect_do_peeling): Remove
redundant and wrong niter bound setting. Move niter
bound adjustment down.
---
gcc/tree-vect-loop-manip.cc | 47 ++++++++++++-------------------------
1 file changed, 15 insertions(+), 32 deletions(-)
@@ -3364,38 +3364,6 @@ vect_do_peeling (loop_vec_info loop_vinfo, tree niters, tree nitersm1,
bb_before_epilog->count = single_pred_edge (bb_before_epilog)->count ();
bb_before_epilog = loop_preheader_edge (epilog)->src;
}
- else
- {
- /* When we do not have a loop-around edge to the epilog we know
- the vector loop covered at least VF scalar iterations unless
- we have early breaks and the epilog will cover at most
- VF - 1 + gap peeling iterations.
- Update any known upper bound with this knowledge. */
- if (! LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
- {
- if (epilog->any_upper_bound)
- epilog->nb_iterations_upper_bound -= lowest_vf;
- if (epilog->any_likely_upper_bound)
- epilog->nb_iterations_likely_upper_bound -= lowest_vf;
- if (epilog->any_estimate)
- epilog->nb_iterations_estimate -= lowest_vf;
- }
- unsigned HOST_WIDE_INT const_vf;
- if (vf.is_constant (&const_vf))
- {
- const_vf += LOOP_VINFO_PEELING_FOR_GAPS (loop_vinfo) - 1;
- if (epilog->any_upper_bound)
- epilog->nb_iterations_upper_bound
- = wi::umin (epilog->nb_iterations_upper_bound, const_vf);
- if (epilog->any_likely_upper_bound)
- epilog->nb_iterations_likely_upper_bound
- = wi::umin (epilog->nb_iterations_likely_upper_bound,
- const_vf);
- if (epilog->any_estimate)
- epilog->nb_iterations_estimate
- = wi::umin (epilog->nb_iterations_estimate, const_vf);
- }
- }
/* If loop is peeled for non-zero constant times, now niters refers to
orig_niters - prolog_peeling, it won't overflow even the orig_niters
@@ -3486,6 +3454,21 @@ vect_do_peeling (loop_vec_info loop_vinfo, tree niters, tree nitersm1,
if (LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
iterate_fix_dominators (CDI_DOMINATORS, doms, false);
+ /* When we do not have a loop-around edge to the epilog we know
+ the vector loop covered at least VF scalar iterations unless
+ we have early breaks.
+ Update any known upper bound with this knowledge. */
+ if (! skip_vector
+ && ! LOOP_VINFO_EARLY_BREAKS (loop_vinfo))
+ {
+ if (epilog->any_upper_bound)
+ epilog->nb_iterations_upper_bound -= lowest_vf;
+ if (epilog->any_likely_upper_bound)
+ epilog->nb_iterations_likely_upper_bound -= lowest_vf;
+ if (epilog->any_estimate)
+ epilog->nb_iterations_estimate -= lowest_vf;
+ }
+
unsigned HOST_WIDE_INT bound;
if (bound_scalar.is_constant (&bound))
{