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[Bug tree-optimization/82397] [8 Regression] qsort comparator non-negative on sorted output: 1 in vect_analyze_data_ref_accesses
- From: "rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 04 Oct 2017 13:36:22 +0000
- Subject: [Bug tree-optimization/82397] [8 Regression] qsort comparator non-negative on sorted output: 1 in vect_analyze_data_ref_accesses
- Auto-submitted: auto-generated
- References: <bug-82397-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82397
--- Comment #4 from rguenther at suse dot de <rguenther at suse dot de> ---
On Wed, 4 Oct 2017, amonakov at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82397
>
> --- Comment #3 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
> Is it possible to simply invoke data_ref_compare_tree always, without checking
> operand_equal_p beforehand? It's possible to canonicalize commutative chains in
> data_ref_compare_tree, or - even better - while generating trees in the first
> place; I don't understand why the operand_equal_p checks are there, they seem
> more costly than what data_ref_compare_tree does.
I believe we exactly left them there because they catches more
equalities and data_ref_compare_tree was supposed to only order
non-equal ones.