[PATCH] Relax invalidation of TOP N counters in PGO.

Jeff Law law@redhat.com
Mon Jan 6 18:05:00 GMT 2020


On Mon, 2020-01-06 at 15:08 +0100, Martin Liška wrote:
> Hi.
> 
> As Honza noticed in the PR, we are quite strict about TOP N
> counter invalidation due to multiple values that can't
> fit in a counter. We due it in order to have a reproducible
> builds. I guess we should do a compromise in between reproducibility
> and possible speed up. That's why I'm suggesting to invalidate
> a TOP N counter only if param_profile_topn_invalid_threshold percent
> of profile are missing.
> 
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> 
> Ready to be installed?
> Thanks,
> Martin
> 
> gcc/ChangeLog:
> 
> 2020-01-06  Martin Liska  <mliska@suse.cz>
> 
> 	PR tree-optimization/92924
> 	* params.opt (param_profile_topn_invalid_threshold):
> 	New parameter.
> 	* profile.c (sort_hist_values): Mark TOP N counter
> 	invalid only if significant amount of samples
> 	is missing.
> 
> gcc/testsuite/ChangeLog:
> 
> 2020-01-06  Martin Liska  <mliska@suse.cz>
> 
> 	PR tree-optimization/92924
> 	* gcc.dg/tree-prof/pr92924-2.c: New test.
> 	* gcc.dg/tree-prof/pr92924.c: New test.
> 
> libgcc/ChangeLog:
> 
> 2020-01-06  Martin Liska  <mliska@suse.cz>
> 
> 	PR tree-optimization/92924
> 	* libgcov-merge.c (merge_topn_values_set): Replace
> 	value with lowest count.
OK
jeff



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