1 /* This file is part of the autovivification Perl module.
2 * See http://search.cpan.org/dist/autovivification/ */
4 #define PERL_NO_GET_CONTEXT
9 #define __PACKAGE__ "autovivification"
10 #define __PACKAGE_LEN__ (sizeof(__PACKAGE__)-1)
12 /* --- Compatibility wrappers ---------------------------------------------- */
14 #define A_HAS_PERL(R, V, S) (PERL_REVISION > (R) || (PERL_REVISION == (R) && (PERL_VERSION > (V) || (PERL_VERSION == (V) && (PERL_SUBVERSION >= (S))))))
16 #ifndef A_WORKAROUND_REQUIRE_PROPAGATION
17 # define A_WORKAROUND_REQUIRE_PROPAGATION !A_HAS_PERL(5, 10, 1)
20 /* --- Helpers ------------------------------------------------------------- */
22 #if A_WORKAROUND_REQUIRE_PROPAGATION
24 #define A_ENCODE_UV(B, U) \
26 while (len < sizeof(UV)) { \
27 (B)[len++] = (U) & 0xFF; \
31 #define A_DECODE_UV(U, B) \
34 (U) = ((U) << 8) | (B)[--len];
36 #if A_WORKAROUND_REQUIRE_PROPAGATION
37 STATIC UV a_require_tag(pTHX) {
38 #define a_require_tag() a_require_tag(aTHX)
41 for (si = PL_curstackinfo; si; si = si->si_prev) {
44 for (cxix = si->si_cxix; cxix >= 0; --cxix) {
45 const PERL_CONTEXT *cx = si->si_cxstack + cxix;
47 if (CxTYPE(cx) == CXt_EVAL && cx->blk_eval.old_op_type == OP_REQUIRE)
54 #endif /* A_WORKAROUND_REQUIRE_PROPAGATION */
56 STATIC SV *a_tag(pTHX_ UV bits) {
57 #define a_tag(B) a_tag(aTHX_ (B))
61 unsigned char buf[sizeof(UV) * 2];
64 cxreq = a_require_tag();
65 A_ENCODE_UV(buf, cxreq);
66 A_ENCODE_UV(buf + sizeof(UV), bits);
67 hint = newSVpvn(buf, sizeof buf);
73 STATIC UV a_detag(pTHX_ const SV *hint) {
74 #define a_detag(H) a_detag(aTHX_ (H))
76 UV cxreq = 0, bits = 0;
80 if (!(hint && SvOK(hint)))
85 A_DECODE_UV(cxreq, buf);
86 if (a_require_tag() != cxreq)
89 A_DECODE_UV(bits, buf + sizeof(UV));
94 #else /* A_WORKAROUND_REQUIRE_PROPAGATION */
96 #define a_tag(B) newSVuv(B)
97 /* PVs fetched from the hints chain have their SvLEN set to zero, so get the UV
104 ? sv_2uv(SvLEN(H) ? (H) : sv_mortalcopy(H)) \
110 #endif /* !A_WORKAROUND_REQUIRE_PROPAGATION */
112 /* Used both for hints and op flags */
113 #define A_HINT_STRICT 1
114 #define A_HINT_WARN 2
115 #define A_HINT_FETCH 4
116 #define A_HINT_STORE 8
117 #define A_HINT_EXISTS 16
118 #define A_HINT_DELETE 32
119 #define A_HINT_NOTIFY (A_HINT_STRICT|A_HINT_WARN)
120 #define A_HINT_DO (A_HINT_FETCH|A_HINT_STORE|A_HINT_EXISTS|A_HINT_DELETE)
121 #define A_HINT_MASK (A_HINT_NOTIFY|A_HINT_DO)
123 /* Only used in op flags */
124 #define A_HINT_ROOT 64
125 #define A_HINT_DEREF 128
127 STATIC U32 a_hash = 0;
129 STATIC UV a_hint(pTHX) {
130 #define a_hint() a_hint(aTHX)
132 #if A_HAS_PERL(5, 9, 5)
133 hint = Perl_refcounted_he_fetch(aTHX_ PL_curcop->cop_hints_hash,
135 __PACKAGE__, __PACKAGE_LEN__,
139 SV **val = hv_fetch(GvHV(PL_hintgv), __PACKAGE__, __PACKAGE_LEN__, a_hash);
144 return a_detag(hint);
147 /* ... op => info map ...................................................... */
155 #define PTABLE_NAME ptable_map
156 #define PTABLE_VAL_FREE(V) PerlMemShared_free(V)
160 /* PerlMemShared_free() needs the [ap]PTBLMS_? default values */
161 #define ptable_map_store(T, K, V) ptable_map_store(aPTBLMS_ (T), (K), (V))
163 STATIC ptable *a_op_map = NULL;
166 STATIC perl_mutex a_op_map_mutex;
169 STATIC const a_op_info *a_map_fetch(const OP *o, a_op_info *oi) {
170 const a_op_info *val;
173 MUTEX_LOCK(&a_op_map_mutex);
176 val = ptable_fetch(a_op_map, o);
183 MUTEX_UNLOCK(&a_op_map_mutex);
189 STATIC const a_op_info *a_map_store_locked(pPTBLMS_ const OP *o, OP *(*old_pp)(pTHX), void *next, UV flags) {
190 #define a_map_store_locked(O, PP, N, F) a_map_store_locked(aPTBLMS_ (O), (PP), (N), (F))
193 if (!(oi = ptable_fetch(a_op_map, o))) {
194 oi = PerlMemShared_malloc(sizeof *oi);
195 ptable_map_store(a_op_map, o, oi);
205 STATIC void a_map_store(pPTBLMS_ const OP *o, OP *(*old_pp)(pTHX), void *next, UV flags) {
206 #define a_map_store(O, PP, N, F) a_map_store(aPTBLMS_ (O), (PP), (N), (F))
209 MUTEX_LOCK(&a_op_map_mutex);
212 a_map_store_locked(o, old_pp, next, flags);
215 MUTEX_UNLOCK(&a_op_map_mutex);
219 STATIC void a_map_delete(pTHX_ const OP *o) {
220 #define a_map_delete(O) a_map_delete(aTHX_ (O))
222 MUTEX_LOCK(&a_op_map_mutex);
225 ptable_map_store(a_op_map, o, NULL);
228 MUTEX_UNLOCK(&a_op_map_mutex);
232 STATIC const OP *a_map_descend(const OP *o) {
233 switch (PL_opargs[o->op_type] & OA_CLASS_MASK) {
237 case OA_BASEOP_OR_UNOP:
238 return cUNOPo->op_first;
241 return cLISTOPo->op_last;
247 STATIC void a_map_store_root(pPTBLMS_ const OP *root, OP *(*old_pp)(pTHX), UV flags) {
248 #define a_map_store_root(R, PP, F) a_map_store_root(aPTBLMS_ (R), (PP), (F))
249 const a_op_info *roi;
254 MUTEX_LOCK(&a_op_map_mutex);
257 roi = a_map_store_locked(o, old_pp, (OP *) root, flags | A_HINT_ROOT);
259 while (o->op_flags & OPf_KIDS) {
260 o = a_map_descend(o);
263 if ((oi = ptable_fetch(a_op_map, o))) {
264 oi->flags &= ~A_HINT_ROOT;
265 oi->next = (a_op_info *) roi;
271 MUTEX_UNLOCK(&a_op_map_mutex);
277 STATIC void a_map_update_flags_topdown(const OP *root, UV flags) {
282 MUTEX_LOCK(&a_op_map_mutex);
285 flags &= ~A_HINT_ROOT;
288 if ((oi = ptable_fetch(a_op_map, o)))
289 oi->flags = (oi->flags & A_HINT_ROOT) | flags;
290 if (!(o->op_flags & OPf_KIDS))
292 o = a_map_descend(o);
296 MUTEX_UNLOCK(&a_op_map_mutex);
302 #define a_map_cancel(R) a_map_update_flags_topdown((R), 0)
304 STATIC void a_map_update_flags_bottomup(const OP *o, UV flags, UV rflags) {
308 MUTEX_LOCK(&a_op_map_mutex);
311 flags &= ~A_HINT_ROOT;
312 rflags |= A_HINT_ROOT;
314 oi = ptable_fetch(a_op_map, o);
315 while (!(oi->flags & A_HINT_ROOT)) {
322 MUTEX_UNLOCK(&a_op_map_mutex);
328 /* ... Decide whether this expression should be autovivified or not ........ */
330 STATIC UV a_map_resolve(const OP *o, a_op_info *oi) {
331 UV flags = 0, rflags;
335 while (!(roi->flags & A_HINT_ROOT))
340 rflags = roi->flags & ~A_HINT_ROOT;
345 if (root->op_flags & OPf_MOD) {
346 if (rflags & A_HINT_STORE)
347 flags = (A_HINT_STORE|A_HINT_DEREF);
348 } else if (rflags & A_HINT_FETCH)
349 flags = (A_HINT_FETCH|A_HINT_DEREF);
353 a_map_update_flags_bottomup(o, 0, 0);
357 flags |= (rflags & A_HINT_NOTIFY);
358 a_map_update_flags_bottomup(o, flags, 0);
360 return oi->flags & A_HINT_ROOT ? 0 : flags;
363 /* ... Lightweight pp_defined() ............................................ */
365 STATIC bool a_defined(pTHX_ SV *sv) {
366 #define a_defined(S) a_defined(aTHX_ (S))
367 bool defined = FALSE;
369 switch (SvTYPE(sv)) {
371 if (AvMAX(sv) >= 0 || SvGMAGICAL(sv)
372 || (SvRMAGICAL(sv) && mg_find(sv, PERL_MAGIC_tied)))
376 if (HvARRAY(sv) || SvGMAGICAL(sv)
377 || (SvRMAGICAL(sv) && mg_find(sv, PERL_MAGIC_tied)))
387 /* --- PP functions -------------------------------------------------------- */
389 /* Be aware that we restore PL_op->op_ppaddr from the pointer table old_pp
390 * value, another extension might have saved our pp replacement as the ppaddr
391 * for this op, so this doesn't ensure that our function will never be called
392 * again. That's why we don't remove the op info from our map, so that it can
393 * still run correctly if required. */
395 /* ... pp_rv2av ............................................................ */
397 STATIC OP *a_pp_rv2av(pTHX) {
402 a_map_fetch(PL_op, &oi);
405 if (flags & A_HINT_DEREF) {
407 /* We always need to push an empty array to fool the pp_aelem() that comes
411 av = sv_2mortal((SV *) newAV());
416 PL_op->op_ppaddr = oi.old_pp;
419 return CALL_FPTR(oi.old_pp)(aTHX);
422 /* ... pp_rv2hv ............................................................ */
424 STATIC OP *a_pp_rv2hv_simple(pTHX) {
429 a_map_fetch(PL_op, &oi);
432 if (flags & A_HINT_DEREF) {
436 PL_op->op_ppaddr = oi.old_pp;
439 return CALL_FPTR(oi.old_pp)(aTHX);
442 STATIC OP *a_pp_rv2hv(pTHX) {
447 a_map_fetch(PL_op, &oi);
450 if (flags & A_HINT_DEREF) {
454 hv = sv_2mortal((SV *) newHV());
459 PL_op->op_ppaddr = oi.old_pp;
462 return CALL_FPTR(oi.old_pp)(aTHX);
465 /* ... pp_deref (aelem,helem,rv2sv,padsv) .................................. */
467 STATIC OP *a_pp_deref(pTHX) {
472 a_map_fetch(PL_op, &oi);
475 if (flags & A_HINT_DEREF) {
480 old_private = PL_op->op_private;
481 PL_op->op_private = ((old_private & ~OPpDEREF) | OPpLVAL_DEFER);
482 o = CALL_FPTR(oi.old_pp)(aTHX);
483 PL_op->op_private = old_private;
485 if (flags & (A_HINT_NOTIFY|A_HINT_STORE)) {
488 if (flags & A_HINT_STRICT)
489 croak("Reference vivification forbidden");
490 else if (flags & A_HINT_WARN)
491 warn("Reference was vivified");
492 else /* A_HINT_STORE */
493 croak("Can't vivify reference");
498 } else if ((flags & ~A_HINT_ROOT)
499 && (PL_op->op_private & OPpDEREF || flags & A_HINT_ROOT)) {
500 /* Decide if the expression must autovivify or not.
501 * This branch should be called only once by expression. */
502 flags = a_map_resolve(PL_op, &oi);
504 /* We need the updated flags value in the deref branch. */
505 if (flags & A_HINT_DEREF)
509 /* This op doesn't need to skip autovivification, so restore the original
511 PL_op->op_ppaddr = oi.old_pp;
513 return CALL_FPTR(oi.old_pp)(aTHX);
516 /* ... pp_root (exists,delete,keys,values) ................................. */
518 STATIC OP *a_pp_root_unop(pTHX) {
522 if (!a_defined(TOPs)) {
524 /* Can only be reached by keys or values */
525 if (GIMME_V == G_SCALAR) {
532 a_map_fetch(PL_op, &oi);
534 return CALL_FPTR(oi.old_pp)(aTHX);
537 STATIC OP *a_pp_root_binop(pTHX) {
541 if (!a_defined(TOPm1s)) {
544 if (PL_op->op_type == OP_EXISTS)
550 a_map_fetch(PL_op, &oi);
552 return CALL_FPTR(oi.old_pp)(aTHX);
555 /* --- Check functions ----------------------------------------------------- */
557 STATIC void a_recheck_rv2xv(pTHX_ OP *o, OPCODE type, OP *(*new_pp)(pTHX)) {
558 #define a_recheck_rv2xv(O, T, PP) a_recheck_rv2xv(aTHX_ (O), (T), (PP))
561 if (o->op_type == type && o->op_ppaddr != new_pp
562 && cUNOPo->op_first->op_type != OP_GV
563 && a_map_fetch(o, &oi)) {
564 a_map_store(o, o->op_ppaddr, oi.next, oi.flags);
565 o->op_ppaddr = new_pp;
571 /* ... ck_pad{any,sv} ...................................................... */
573 /* Sadly, the PADSV OPs we are interested in don't trigger the padsv check
574 * function, but are instead manually mutated from a PADANY. This is why we set
575 * PL_ppaddr[OP_PADSV] in the padany check function so that PADSV OPs will have
576 * their op_ppaddr set to our pp_padsv. PL_ppaddr[OP_PADSV] is then reset at the
577 * beginning of every ck_pad{any,sv}. Some unwanted OPs can still call our
578 * pp_padsv, but much less than if we would have set PL_ppaddr[OP_PADSV]
581 STATIC OP *(*a_pp_padsv_saved)(pTHX) = 0;
583 STATIC void a_pp_padsv_save(void) {
584 if (a_pp_padsv_saved)
587 a_pp_padsv_saved = PL_ppaddr[OP_PADSV];
588 PL_ppaddr[OP_PADSV] = a_pp_deref;
591 STATIC void a_pp_padsv_restore(OP *o) {
592 if (!a_pp_padsv_saved)
595 if (o->op_ppaddr == a_pp_deref)
596 o->op_ppaddr = a_pp_padsv_saved;
598 PL_ppaddr[OP_PADSV] = a_pp_padsv_saved;
599 a_pp_padsv_saved = 0;
602 STATIC OP *(*a_old_ck_padany)(pTHX_ OP *) = 0;
604 STATIC OP *a_ck_padany(pTHX_ OP *o) {
607 a_pp_padsv_restore(o);
609 o = CALL_FPTR(a_old_ck_padany)(aTHX_ o);
612 if (hint & A_HINT_DO) {
614 a_map_store_root(o, a_pp_padsv_saved, hint);
621 STATIC OP *(*a_old_ck_padsv)(pTHX_ OP *) = 0;
623 STATIC OP *a_ck_padsv(pTHX_ OP *o) {
626 a_pp_padsv_restore(o);
628 o = CALL_FPTR(a_old_ck_padsv)(aTHX_ o);
631 if (hint & A_HINT_DO) {
632 a_map_store_root(o, o->op_ppaddr, hint);
633 o->op_ppaddr = a_pp_deref;
640 /* ... ck_deref (aelem,helem,rv2sv) ........................................ */
642 /* Those ops appear both at the root and inside an expression but there's no
643 * way to distinguish both situations. Worse, we can't even know if we are in a
644 * modifying context, so the expression can't be resolved yet. It will be at the
645 * first invocation of a_pp_deref() for this expression. */
647 STATIC OP *(*a_old_ck_aelem)(pTHX_ OP *) = 0;
648 STATIC OP *(*a_old_ck_helem)(pTHX_ OP *) = 0;
649 STATIC OP *(*a_old_ck_rv2sv)(pTHX_ OP *) = 0;
651 STATIC OP *a_ck_deref(pTHX_ OP *o) {
652 OP * (*old_ck)(pTHX_ OP *o) = 0;
655 switch (o->op_type) {
657 old_ck = a_old_ck_aelem;
658 if ((hint & A_HINT_DO) && !(hint & A_HINT_STRICT))
659 a_recheck_rv2xv(cUNOPo->op_first, OP_RV2AV, a_pp_rv2av);
662 old_ck = a_old_ck_helem;
663 if ((hint & A_HINT_DO) && !(hint & A_HINT_STRICT))
664 a_recheck_rv2xv(cUNOPo->op_first, OP_RV2HV, a_pp_rv2hv_simple);
667 old_ck = a_old_ck_rv2sv;
670 o = CALL_FPTR(old_ck)(aTHX_ o);
672 if (hint & A_HINT_DO) {
673 a_map_store_root(o, o->op_ppaddr, hint);
674 o->op_ppaddr = a_pp_deref;
681 /* ... ck_rv2xv (rv2av,rv2hv) .............................................. */
683 /* Those ops also appear both inisde and at the root, hence the caveats for
684 * a_ck_deref() still apply here. Since a padsv/rv2sv must appear before a
685 * rv2[ah]v, resolution is handled by the first call to a_pp_deref() in the
688 STATIC OP *(*a_old_ck_rv2av)(pTHX_ OP *) = 0;
689 STATIC OP *(*a_old_ck_rv2hv)(pTHX_ OP *) = 0;
691 STATIC OP *a_ck_rv2xv(pTHX_ OP *o) {
692 OP * (*old_ck)(pTHX_ OP *o) = 0;
693 OP * (*new_pp)(pTHX) = 0;
696 switch (o->op_type) {
697 case OP_RV2AV: old_ck = a_old_ck_rv2av; new_pp = a_pp_rv2av; break;
698 case OP_RV2HV: old_ck = a_old_ck_rv2hv; new_pp = a_pp_rv2hv_simple; break;
700 o = CALL_FPTR(old_ck)(aTHX_ o);
702 if (cUNOPo->op_first->op_type == OP_GV)
706 if (hint & A_HINT_DO && !(hint & A_HINT_STRICT)) {
707 a_map_store_root(o, o->op_ppaddr, hint);
708 o->op_ppaddr = new_pp;
715 /* ... ck_xslice (aslice,hslice) ........................................... */
717 /* I think those are only found at the root, but there's nothing that really
718 * prevent them to be inside the expression too. We only need to update the
719 * root so that the rest of the expression will see the right context when
720 * resolving. That's why we don't replace the ppaddr. */
722 STATIC OP *(*a_old_ck_aslice)(pTHX_ OP *) = 0;
723 STATIC OP *(*a_old_ck_hslice)(pTHX_ OP *) = 0;
725 STATIC OP *a_ck_xslice(pTHX_ OP *o) {
726 OP * (*old_ck)(pTHX_ OP *o) = 0;
729 switch (o->op_type) {
731 old_ck = a_old_ck_aslice;
734 old_ck = a_old_ck_hslice;
735 if (hint & A_HINT_DO)
736 a_recheck_rv2xv(cUNOPo->op_first->op_sibling, OP_RV2HV, a_pp_rv2hv);
739 o = CALL_FPTR(old_ck)(aTHX_ o);
741 if (hint & A_HINT_DO) {
742 a_map_store_root(o, 0, hint);
749 /* ... ck_root (exists,delete,keys,values) ................................. */
751 /* Those ops are only found at the root of a dereferencing expression. We can
752 * then resolve at compile time if vivification must take place or not. */
754 STATIC OP *(*a_old_ck_exists)(pTHX_ OP *) = 0;
755 STATIC OP *(*a_old_ck_delete)(pTHX_ OP *) = 0;
756 STATIC OP *(*a_old_ck_keys) (pTHX_ OP *) = 0;
757 STATIC OP *(*a_old_ck_values)(pTHX_ OP *) = 0;
759 STATIC OP *a_ck_root(pTHX_ OP *o) {
760 OP * (*old_ck)(pTHX_ OP *o) = 0;
761 OP * (*new_pp)(pTHX) = 0;
762 bool enabled = FALSE;
765 switch (o->op_type) {
767 old_ck = a_old_ck_exists;
768 new_pp = a_pp_root_binop;
769 enabled = hint & A_HINT_EXISTS;
772 old_ck = a_old_ck_delete;
773 new_pp = a_pp_root_binop;
774 enabled = hint & A_HINT_DELETE;
777 old_ck = a_old_ck_keys;
778 new_pp = a_pp_root_unop;
779 enabled = hint & A_HINT_FETCH;
782 old_ck = a_old_ck_values;
783 new_pp = a_pp_root_unop;
784 enabled = hint & A_HINT_FETCH;
787 o = CALL_FPTR(old_ck)(aTHX_ o);
789 if (hint & A_HINT_DO) {
791 a_map_update_flags_topdown(o, hint | A_HINT_DEREF);
792 a_map_store_root(o, o->op_ppaddr, hint);
793 o->op_ppaddr = new_pp;
803 STATIC U32 a_initialized = 0;
805 /* --- XS ------------------------------------------------------------------ */
807 MODULE = autovivification PACKAGE = autovivification
813 if (!a_initialized++) {
816 a_op_map = ptable_new();
818 MUTEX_INIT(&a_op_map_mutex);
821 PERL_HASH(a_hash, __PACKAGE__, __PACKAGE_LEN__);
823 a_old_ck_padany = PL_check[OP_PADANY];
824 PL_check[OP_PADANY] = MEMBER_TO_FPTR(a_ck_padany);
825 a_old_ck_padsv = PL_check[OP_PADSV];
826 PL_check[OP_PADSV] = MEMBER_TO_FPTR(a_ck_padsv);
828 a_old_ck_aelem = PL_check[OP_AELEM];
829 PL_check[OP_AELEM] = MEMBER_TO_FPTR(a_ck_deref);
830 a_old_ck_helem = PL_check[OP_HELEM];
831 PL_check[OP_HELEM] = MEMBER_TO_FPTR(a_ck_deref);
832 a_old_ck_rv2sv = PL_check[OP_RV2SV];
833 PL_check[OP_RV2SV] = MEMBER_TO_FPTR(a_ck_deref);
835 a_old_ck_rv2av = PL_check[OP_RV2AV];
836 PL_check[OP_RV2AV] = MEMBER_TO_FPTR(a_ck_rv2xv);
837 a_old_ck_rv2hv = PL_check[OP_RV2HV];
838 PL_check[OP_RV2HV] = MEMBER_TO_FPTR(a_ck_rv2xv);
840 a_old_ck_aslice = PL_check[OP_ASLICE];
841 PL_check[OP_ASLICE] = MEMBER_TO_FPTR(a_ck_xslice);
842 a_old_ck_hslice = PL_check[OP_HSLICE];
843 PL_check[OP_HSLICE] = MEMBER_TO_FPTR(a_ck_xslice);
845 a_old_ck_exists = PL_check[OP_EXISTS];
846 PL_check[OP_EXISTS] = MEMBER_TO_FPTR(a_ck_root);
847 a_old_ck_delete = PL_check[OP_DELETE];
848 PL_check[OP_DELETE] = MEMBER_TO_FPTR(a_ck_root);
849 a_old_ck_keys = PL_check[OP_KEYS];
850 PL_check[OP_KEYS] = MEMBER_TO_FPTR(a_ck_root);
851 a_old_ck_values = PL_check[OP_VALUES];
852 PL_check[OP_VALUES] = MEMBER_TO_FPTR(a_ck_root);
854 stash = gv_stashpvn(__PACKAGE__, __PACKAGE_LEN__, 1);
855 newCONSTSUB(stash, "A_HINT_STRICT", newSVuv(A_HINT_STRICT));
856 newCONSTSUB(stash, "A_HINT_WARN", newSVuv(A_HINT_WARN));
857 newCONSTSUB(stash, "A_HINT_FETCH", newSVuv(A_HINT_FETCH));
858 newCONSTSUB(stash, "A_HINT_STORE", newSVuv(A_HINT_STORE));
859 newCONSTSUB(stash, "A_HINT_EXISTS", newSVuv(A_HINT_EXISTS));
860 newCONSTSUB(stash, "A_HINT_DELETE", newSVuv(A_HINT_DELETE));
861 newCONSTSUB(stash, "A_HINT_MASK", newSVuv(A_HINT_MASK));
869 RETVAL = a_tag(SvOK(hint) ? SvUV(hint) : 0);
879 RETVAL = newSVuv(a_detag(tag));