[Bug tree-optimization/81292] [8 regression] ICE in zero_length_string, at tree-ssa-strlen.c:822

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81292

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rsandifo at gcc dot gnu.org

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The problem is that we hit:
      if (si != NULL)
        {
          if (!si->full_string_p && !si->stmt)
            {
              /* Until now we only had a lower bound on the string length.
                 Install LHS as the actual length.  */
              si = unshare_strinfo (si);
              si->nonzero_chars = lhs;
              si->full_string_p = true;
            }
          return;
        }
in handle_builtin_strlen, which changes just that single strinfo record, but
doesn't do anything for the related ones.  And as strlen doesn't have a vdef
(it is a pure function), nothing is invalidated, so we end up with a mixture of
related strinfos where some strinfos are full_string_p and others are not, and
e.g. zero_length_string has asserts that this does not happen.
So, either handle_builtin_strlen needs to adjust also the related strinfos if
any (note, maybe even if verify_related_strinfos fails we might need to do that
or invalidate them manually), or we need to invalidate them, or not to record
this change if we can't adjust or invalidate them all.