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From: "guojiufu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/102072] New test case
 gcc.dg/vect/pr101145_3.c in r12-3136 fails on armeb
Date: Fri, 27 Aug 2021 09:00:09 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102072

--- Comment #7 from Jiu Fu Guo <guojiufu at gcc dot gnu.org> ---
For this case: it was generated as:
  l_12 =3D l_25 + 1;
  if (l_12 > n_13(D))

Here: cmp is ">", bound is "n_13", and "iv(base=3Dl_xx, step=3D1)".
This hits the assert in determine_exit_conditions.

For members of tree_niter_desc, the comments(as below) align with the asser=
ts
in determine_exit_conditions.=20
------------
  /* The simplified shape of the exit condition.  The loop exits if=20=20=
=20=20=20=20=20=20=20=20=20=20=20
     CONTROL CMP BOUND is false, where CMP is one of NE_EXPR,=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
     LT_EXPR, or GT_EXPR, and step of CONTROL is positive if CMP is=20=20=
=20=20=20=20=20=20=20=20=20=20=20
     LE_EXPR and negative if CMP is GE_EXPR.  This information is used=20=
=20=20=20=20=20=20=20=20=20
     by loop unrolling.  */
  affine_iv control;
  tree bound;
  enum tree_code cmp;


Current code the "control, bound and cmp" are set in number_of_iterations_l=
t:
    if (integer_nonzerop (iv0->step))
      {=20=20
        niter->control =3D *iv0;
        niter->cmp =3D LT_EXPR;
        niter->bound =3D iv1->base;
      }
    else
      {
        niter->control =3D *iv1;
        niter->cmp =3D GT_EXPR;
        niter->bound =3D iv0->base;
      }
This code may need to refine for the case "step until wrap condition".=