* Fix profile update in tail merging
@ 2017-06-16 17:47 Jan Hubicka
0 siblings, 0 replies; only message in thread
From: Jan Hubicka @ 2017-06-16 17:47 UTC (permalink / raw)
To: gcc-patches
Hi,
profile updating in tail merging is completely wrong when profile feedback
is missing or 0. This fixes it hopefully reasonably.
Bootstrapped/regtested x86_64-linux.
Honza
* tree-ssa-tail-merge.c (replace_block_by): Fix profile updating.
Index: tree-ssa-tail-merge.c
===================================================================
--- tree-ssa-tail-merge.c (revision 249244)
+++ tree-ssa-tail-merge.c (working copy)
@@ -1555,29 +1555,51 @@ replace_block_by (basic_block bb1, basic
pred_edge, UNKNOWN_LOCATION);
}
- bb2->frequency += bb1->frequency;
- if (bb2->frequency > BB_FREQ_MAX)
- bb2->frequency = BB_FREQ_MAX;
-
bb2->count += bb1->count;
/* Merge the outgoing edge counts from bb1 onto bb2. */
profile_count out_sum = profile_count::zero ();
+ int out_freq_sum = 0;
+
+ /* 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);
e2->count += e1->count;
+ if (out_sum > 0 && e2->count.initialized_p ())
+ {
+ e2->probability = e2->count.probability_in (bb2->count);
+ }
+ else if (bb1->frequency && bb2->frequency)
+ e2->probability = e1->probability;
+ else if (bb2->frequency && !bb1->frequency)
+ ;
+ else if (out_freq_sum)
+ e2->probability = GCOV_COMPUTE_SCALE (EDGE_FREQUENCY (e1)
+ + EDGE_FREQUENCY (e2),
+ out_freq_sum);
out_sum += e2->count;
}
- /* 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 (e2, ei, bb2->succs)
- {
- e2->probability = e2->count.probability_in (out_sum);
- }
+ bb2->frequency += bb1->frequency;
+ if (bb2->frequency > BB_FREQ_MAX)
+ bb2->frequency = BB_FREQ_MAX;
/* Move over any user labels from bb1 after the bb2 labels. */
gimple_stmt_iterator gsi1 = gsi_start_bb (bb1);
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2017-06-16 17:47 Fix profile update in tail merging Jan Hubicka
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