STATIC void
S_simplify_sort(pTHX_ OP *o)
{
    dVAR;
    OP *kid = cLISTOPo->op_first->op_sibling;	/* get past pushmark */
    OP *k;
    int descending;
    GV *gv;
    const char *gvname;
    bool have_scopeop;

    PERL_ARGS_ASSERT_SIMPLIFY_SORT;

    if (!(o->op_flags & OPf_STACKED))
	return;
    GvMULTI_on(gv_fetchpvs("a", GV_ADD|GV_NOTQUAL, SVt_PV));
    GvMULTI_on(gv_fetchpvs("b", GV_ADD|GV_NOTQUAL, SVt_PV));
    ...