+/* ... Thread-safe hints ................................................... */
+
+#if LT_WORKAROUND_REQUIRE_PROPAGATION
+
+typedef struct {
+ SV *code;
+ IV require_tag;
+} lt_hint_t;
+
+#define LT_HINT_STRUCT 1
+
+#define LT_HINT_CODE(H) ((H)->code)
+
+#define LT_HINT_FREE(H) { \
+ lt_hint_t *h = (H); \
+ SvREFCNT_dec(h->code); \
+ PerlMemShared_free(h); \
+}
+
+#else /* LT_WORKAROUND_REQUIRE_PROPAGATION */
+
+typedef SV lt_hint_t;
+
+#define LT_HINT_STRUCT 0
+
+#define LT_HINT_CODE(H) (H)
+
+#define LT_HINT_FREE(H) SvREFCNT_dec(H);
+
+#endif /* !LT_WORKAROUND_REQUIRE_PROPAGATION */
+
+#if LT_THREADSAFE
+
+#define PTABLE_NAME ptable_hints
+#define PTABLE_VAL_FREE(V) LT_HINT_FREE(V)
+
+#define pPTBL pTHX
+#define pPTBL_ pTHX_
+#define aPTBL aTHX
+#define aPTBL_ aTHX_
+
+#include "ptable.h"
+
+#define ptable_hints_store(T, K, V) ptable_hints_store(aTHX_ (T), (K), (V))
+#define ptable_hints_free(T) ptable_hints_free(aTHX_ (T))
+
+#endif /* LT_THREADSAFE */
+
+/* ... "Seen" pointer table ................................................ */
+
+#define PTABLE_NAME ptable_seen
+#define PTABLE_VAL_FREE(V) NOOP
+
+#include "ptable.h"
+
+/* PerlMemShared_free() needs the [ap]PTBLMS_? default values */
+#define ptable_seen_store(T, K, V) ptable_seen_store(aPTBLMS_ (T), (K), (V))
+#define ptable_seen_clear(T) ptable_seen_clear(aPTBLMS_ (T))
+#define ptable_seen_free(T) ptable_seen_free(aPTBLMS_ (T))
+
+/* ... Global data ......................................................... */
+
+#define MY_CXT_KEY __PACKAGE__ "::_guts" XS_VERSION
+
+typedef struct {
+#if LT_THREADSAFE
+ ptable *tbl; /* It really is a ptable_hints */
+ tTHX owner;
+#endif
+ ptable *seen; /* It really is a ptable_seen */
+ SV *default_meth;
+} my_cxt_t;
+
+START_MY_CXT
+
+/* ... Cloning global data ................................................. */
+
+#if LT_THREADSAFE
+
+typedef struct {
+ ptable *tbl;
+#if LT_HAS_PERL(5, 13, 2)
+ CLONE_PARAMS *params;
+#else
+ CLONE_PARAMS params;
+#endif
+} lt_ptable_clone_ud;
+
+#if LT_HAS_PERL(5, 13, 2)
+# define lt_ptable_clone_ud_init(U, T, O) \
+ (U).tbl = (T); \
+ (U).params = Perl_clone_params_new((O), aTHX)
+# define lt_ptable_clone_ud_deinit(U) Perl_clone_params_del((U).params)
+# define lt_dup_inc(S, U) SvREFCNT_inc(sv_dup((S), (U)->params))
+#else
+# define lt_ptable_clone_ud_init(U, T, O) \
+ (U).tbl = (T); \
+ (U).params.stashes = newAV(); \
+ (U).params.flags = 0; \
+ (U).params.proto_perl = (O)
+# define lt_ptable_clone_ud_deinit(U) SvREFCNT_dec((U).params.stashes)
+# define lt_dup_inc(S, U) SvREFCNT_inc(sv_dup((S), &((U)->params)))
+#endif
+
+STATIC void lt_ptable_clone(pTHX_ ptable_ent *ent, void *ud_) {
+ lt_ptable_clone_ud *ud = ud_;
+ lt_hint_t *h1 = ent->val;
+ lt_hint_t *h2;
+
+#if LT_HINT_STRUCT
+
+ h2 = PerlMemShared_malloc(sizeof *h2);
+ h2->code = lt_dup_inc(h1->code, ud);
+#if LT_WORKAROUND_REQUIRE_PROPAGATION
+ h2->require_tag = PTR2IV(lt_dup_inc(INT2PTR(SV *, h1->require_tag), ud));
+#endif
+
+#else /* LT_HINT_STRUCT */
+
+ h2 = lt_dup_inc(h1, ud);
+
+#endif /* !LT_HINT_STRUCT */
+
+ ptable_hints_store(ud->tbl, ent->key, h2);
+}
+
+STATIC void lt_thread_cleanup(pTHX_ void *ud) {
+ dMY_CXT;
+
+ ptable_hints_free(MY_CXT.tbl);
+ MY_CXT.tbl = NULL;
+ ptable_seen_free(MY_CXT.seen);
+ MY_CXT.seen = NULL;
+ SvREFCNT_dec(MY_CXT.default_meth);
+ MY_CXT.default_meth = NULL;
+}
+
+STATIC int lt_endav_free(pTHX_ SV *sv, MAGIC *mg) {
+ SAVEDESTRUCTOR_X(lt_thread_cleanup, NULL);
+
+ return 0;
+}
+
+STATIC MGVTBL lt_endav_vtbl = {
+ 0,
+ 0,
+ 0,
+ 0,
+ lt_endav_free
+#if MGf_COPY
+ , 0
+#endif
+#if MGf_DUP
+ , 0
+#endif
+#if MGf_LOCAL
+ , 0
+#endif
+};
+
+#endif /* LT_THREADSAFE */
+
+/* ... Hint tags ........................................................... */
+
+#if LT_WORKAROUND_REQUIRE_PROPAGATION
+
+STATIC IV lt_require_tag(pTHX) {
+#define lt_require_tag() lt_require_tag(aTHX)
+ const CV *cv, *outside;
+
+ cv = PL_compcv;
+
+ if (!cv) {
+ /* If for some reason the pragma is operational at run-time, try to discover
+ * the current cv in use. */
+ const PERL_SI *si;
+
+ for (si = PL_curstackinfo; si; si = si->si_prev) {
+ I32 cxix;
+
+ for (cxix = si->si_cxix; cxix >= 0; --cxix) {
+ const PERL_CONTEXT *cx = si->si_cxstack + cxix;
+
+ switch (CxTYPE(cx)) {
+ case CXt_SUB:
+ case CXt_FORMAT:
+ /* The propagation workaround is only needed up to 5.10.0 and at that
+ * time format and sub contexts were still identical. And even later the
+ * cv members offsets should have been kept the same. */
+ cv = cx->blk_sub.cv;
+ goto get_enclosing_cv;
+ case CXt_EVAL:
+ cv = cx->blk_eval.cv;
+ goto get_enclosing_cv;
+ default:
+ break;
+ }
+ }
+ }
+
+ cv = PL_main_cv;
+ }
+
+get_enclosing_cv:
+ for (outside = CvOUTSIDE(cv); outside; outside = CvOUTSIDE(cv))
+ cv = outside;
+
+ return PTR2IV(cv);
+}
+
+#endif /* LT_WORKAROUND_REQUIRE_PROPAGATION */
+
+STATIC SV *lt_tag(pTHX_ SV *value) {
+#define lt_tag(V) lt_tag(aTHX_ (V))
+ lt_hint_t *h;
+ SV *code = NULL;
+
+ if (SvROK(value)) {
+ value = SvRV(value);
+ if (SvTYPE(value) >= SVt_PVCV) {
+ code = value;
+ SvREFCNT_inc_simple_void_NN(code);
+ }
+ }
+
+#if LT_HINT_STRUCT
+ h = PerlMemShared_malloc(sizeof *h);
+ h->code = code;
+# if LT_WORKAROUND_REQUIRE_PROPAGATION
+ h->require_tag = lt_require_tag();
+# endif /* LT_WORKAROUND_REQUIRE_PROPAGATION */
+#else /* LT_HINT_STRUCT */
+ h = code;
+#endif /* !LT_HINT_STRUCT */
+
+#if LT_THREADSAFE
+ {
+ dMY_CXT;
+ /* We only need for the key to be an unique tag for looking up the value later
+ * Allocated memory provides convenient unique identifiers, so that's why we
+ * use the hint as the key itself. */
+ ptable_hints_store(MY_CXT.tbl, h, h);
+ }
+#endif /* LT_THREADSAFE */
+
+ return newSViv(PTR2IV(h));
+}
+
+STATIC SV *lt_detag(pTHX_ const SV *hint) {
+#define lt_detag(H) lt_detag(aTHX_ (H))
+ lt_hint_t *h;
+#if LT_THREADSAFE
+ dMY_CXT;
+#endif
+
+ if (!(hint && SvIOK(hint)))
+ return NULL;
+
+ h = INT2PTR(lt_hint_t *, SvIVX(hint));
+#if LT_THREADSAFE
+ h = ptable_fetch(MY_CXT.tbl, h);
+#endif /* LT_THREADSAFE */
+#if LT_WORKAROUND_REQUIRE_PROPAGATION
+ if (lt_require_tag() != h->require_tag)
+ return NULL;
+#endif /* LT_WORKAROUND_REQUIRE_PROPAGATION */
+
+ return LT_HINT_CODE(h);
+}