Hi,
this patch re-implements profile update in tail merge which I disabled while
converting CFG to profile counts. This is quite easy to do because one only
scales probabilities relative to cfg counts.
I have stopped on the logic that recomputes counts from edges because it no
longer makes much sense (becuase counts are computed from probabilities)
and wanted to look deeper into what the code is trying to achieve. I hope
it is safe to drop now.
Bootstrapped/regtested x86_64-linux
Honza
* tree-ssa-tail-merge.c (replace_block_by): Fix and re-enable profile
merging.
Index: tree-ssa-tail-merge.c
===================================================================
--- tree-ssa-tail-merge.c (revision 254649)
+++ tree-ssa-tail-merge.c (working copy)
@@ -1556,52 +1556,33 @@ replace_block_by (basic_block bb1, basic
pred_edge, UNKNOWN_LOCATION);
}
- bb2->count += bb1->count;
- /* FIXME: Fix merging of probabilities. They need to be redistributed
- according to the relative counts of merged BBs. */
-#if 0
/* Merge the outgoing edge counts from bb1 onto bb2. */
- profile_count out_sum = profile_count::zero ();
- int out_freq_sum = 0;
edge e1, e2;
+ edge_iterator ei;
- /* Recompute the edge probabilities from the new merged edge count.
- Use the sum of the new merged edge counts computed above instead
- of bb2's merged count, in case there are profile count insanities
- making the bb count inconsistent with the edge weights. */
- FOR_EACH_EDGE (e1, ei, bb1->succs)
- {
- if (e1->count ().initialized_p ())
- out_sum += e1->count ();
- out_freq_sum += EDGE_FREQUENCY (e1);
- }
- FOR_EACH_EDGE (e1, ei, bb2->succs)
- {
- if (e1->count ().initialized_p ())
- out_sum += e1->count ();
- out_freq_sum += EDGE_FREQUENCY (e1);
- }
- FOR_EACH_EDGE (e1, ei, bb1->succs)
- {
- e2 = find_edge (bb2, e1->dest);
- gcc_assert (e2);
- if (out_sum > 0 && e2->count ().initialized_p ())
- {
- e2->probability = e2->count ().probability_in (bb2->count);
- }
- else if (bb1->count.to_frequency (cfun) && bb2->count.to_frequency
(cfun))
- e2->probability = e1->probability;
- else if (bb2->count.to_frequency (cfun) && !bb1->count.to_frequency
(cfun))
- ;
- else if (out_freq_sum)
- e2->probability = profile_probability::from_reg_br_prob_base
- (GCOV_COMPUTE_SCALE (EDGE_FREQUENCY (e1)
- + EDGE_FREQUENCY (e2),
- out_freq_sum));
- out_sum += e2->count ();
- }
-#endif
+ if (bb2->count.initialized_p ())
+ FOR_EACH_EDGE (e1, ei, bb1->succs)
+ {
+ e2 = find_edge (bb2, e1->dest);
+ gcc_assert (e2);
+
+ /* If probabilities are same, we are done.
+ If counts are nonzero we can distribute accordingly. In remaining
+ cases just avreage the values and hope for the best. */
+ if (e1->probability == e2->probability)
+ ;
+ else if (bb1->count.nonzero_p () || bb2->count.nonzero_p ())
+ e2->probability
+ = e2->probability
+ * bb2->count.probability_in (bb1->count + bb2->count)
+ + e1->probability
+ * bb1->count.probability_in (bb1->count + bb2->count);
+ else
+ e2->probability = e2->probability * profile_probability::even ()
+ + e1->probability * profile_probability::even ();
+ }
+ bb2->count += bb1->count;
/* Move over any user labels from bb1 after the bb2 labels. */
gimple_stmt_iterator gsi1 = gsi_start_bb (bb1);
