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From: "asolokha at gmx dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/103254] New: [12 Regression] Compile time hog
 in compare_values_warnv
Date: Mon, 15 Nov 2021 17:27:53 +0000
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X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: compile-time-hog
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103254

            Bug ID: 103254
           Summary: [12 Regression] Compile time hog in
                    compare_values_warnv
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: compile-time-hog
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

gcc-12.0.0-alpha20111107 snapshot (g:962ff7d2849e1fa6a1fe0535aa2dec5c2b9a32=
a6)
takes indefinite time to compile the following testcase w/ -O3:

short int i;

void
foo (void)
{
  for (i =3D 1; i < 2; i +=3D 4)
    {
      int j;

      for (j =3D 0; j < 5; j +=3D 4)
        {
          int k;

          for (k =3D 0; k < 68; k +=3D 4)
            {
              i &=3D j;
              j &=3D i;
            }
        }
    }
}

% timeout 10 gcc-12.0.0 -O3 -c mgyelpiv.c
zsh: exit 124   timeout 10 gcc-12.0.0 -O3 -c mgyelpiv.c

Several top entries from perf top output:

   8.03%  cc1        [.] wide_int_to_tree_1
   5.93%  cc1        [.] compare_values_warnv
   5.38%  cc1        [.] irange::irange_union
   4.72%  cc1        [.] irange::varying_compatible_p
   4.34%  cc1        [.] wi::to_wide
   3.23%  cc1        [.] irange::irange_intersect
   3.12%  cc1        [.] tree_int_cst_compare
   3.07%  cc1        [.] wi::force_to_size
   2.76%  cc1        [.] useless_type_conversion_p
   2.67%  cc1        [.] irange::lower_bound
   2.38%  cc1        [.] irange::set_varying
   2.31%  cc1        [.] wi::shifted_mask
   2.17%  cc1        [.] get_single_symbol
   1.91%  cc1        [.] int_cst_hasher::hash
   1.86%  cc1        [.] irange::verify_range
   1.84%  cc1        [.] wi::min_value
   1.84%  cc1        [.] irange::irange_set_anti_range
   1.63%  cc1        [.] wi::lts_p<generic_wide_int<wide_int_ref_storage<fa=
lse,
false> >, generic_wide_int<wide_int_ref_storage<false, f
   1.46%  cc1        [.] operand_compare::operand_equal_p
   1.37%  cc1        [.] operator_cast::fold_pair
   1.35%  cc1        [.] gori_compute::compute_operand_range=