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From: "hjl.tools at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug driver/108196] New: Incorrect binary search in find_opt
Date: Wed, 21 Dec 2022 20:10:22 +0000
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X-Bugzilla-Version: 13.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108196

            Bug ID: 108196
           Summary: Incorrect binary search in find_opt
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: driver
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
  Target Milestone: ---

opts-common.cc has

  /* Find mn such this lexicographical inequality holds:
     cl_options[mn] <=3D input < cl_options[mn + 1].  */
  while (mx - mn > 1)
    {
      md =3D (mn + mx) / 2;
      opt_len =3D cl_options[md].opt_len;
      comp =3D strncmp (input, cl_options[md].opt_text + 1, opt_len);

      if (comp < 0)
        mx =3D md;
      else
        mn =3D md;
    }

When md is the exact match, the search doesn't terminate and we may get the
wrong result.=