[gcc r12-5910] Avoid updating hot bb threshold in call speculation code

Jan Hubicka hubicka@gcc.gnu.org
Sat Dec 11 19:45:23 GMT 2021


https://gcc.gnu.org/g:2f217f7218b621fd7d7fb7ac59b2ddf2e027ed4a

commit r12-5910-g2f217f7218b621fd7d7fb7ac59b2ddf2e027ed4a
Author: Jan Hubicka <jh@suse.cz>
Date:   Sat Dec 11 20:45:02 2021 +0100

    Avoid updating hot bb threshold in call speculation code
    
    This patch removes apparently forgotten debugging hack (which got in during
    the speculative call patchset) which reduces hot bb threshold.  This does not
    make sense since it is set and reset randomly as the summaries are processed.
    One problem is that we set the BB threshold to make certain BBs hot and hten
    unrolling or vectorization may reduce it to some fraction of the count that
    makes it cold.  We may want to add some buffer and divide the value by,
    say 32, but that shoulid be done independently of speculative calls.
    
    gcc/ChangeLog:
    
    2021-12-11  Jan Hubicka  <hubicka@ucw.cz>
    
            * ipa-profile.c (ipa_profile): Do not update hot bb threshold.

Diff:
---
 gcc/ipa-profile.c | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/gcc/ipa-profile.c b/gcc/ipa-profile.c
index ce32b538976..02f42d9b0f7 100644
--- a/gcc/ipa-profile.c
+++ b/gcc/ipa-profile.c
@@ -854,18 +854,6 @@ ipa_profile (void)
 	      node_map_initialized = true;
 	      ncommon++;
 
-	      if (in_lto_p)
-		{
-		  if (dump_file)
-		    {
-		      fprintf (dump_file,
-			       "Updating hotness threshold in LTO mode.\n");
-		      fprintf (dump_file, "Updated min count: %" PRId64 "\n",
-			       (int64_t) threshold / spec_count);
-		    }
-		  set_hot_bb_threshold (threshold / spec_count);
-		}
-
 	      unsigned speculative_id = 0;
 	      profile_count orig = e->count;
 	      for (unsigned i = 0; i < spec_count; i++)


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