X-Git-Url: http://git.vpit.fr/?p=perl%2Fmodules%2FScope-Upper.git;a=blobdiff_plain;f=Upper.xs;h=efc799ab07f3baa44db5375b493261c05fbf4f49;hp=0ae07f085059f5729a2342bc3ea965f0a98ea6ae;hb=f0ee3a495f7f12754a9e79ef83f9affc69ad2f66;hpb=c6e995c68b5384510061cde2d433e9506a3935f5

diff --git a/Upper.xs b/Upper.xs
index 0ae07f0..efc799a 100644
--- a/Upper.xs
+++ b/Upper.xs
@@ -6,21 +6,21 @@
 #include "perl.h"
 #include "XSUB.h"
 
-#define __PACKAGE__ "Scope::Upper"
+/* --- XS helpers ---------------------------------------------------------- */
 
-#ifndef SU_DEBUG
-# define SU_DEBUG 0
-#endif
+#define XSH_PACKAGE "Scope::Upper"
+
+#include "xsh/caps.h"
+#include "xsh/util.h"
+#include "xsh/debug.h"
 
 /* --- Compatibility ------------------------------------------------------- */
 
-#ifndef NOOP
-# define NOOP
+/* perl 5.23.8 onwards has a revamped context system */
+#if XSH_HAS_PERL(5, 23, 8)
+# define SU_HAS_NEW_CXT
 #endif
 
-#ifndef dNOOP
-# define dNOOP
-#endif
 
 #ifndef dVAR
 # define dVAR dNOOP
@@ -42,20 +42,6 @@
 # define PERL_UNUSED_VAR(V)
 #endif
 
-#ifndef STMT_START
-# define STMT_START do
-#endif
-
-#ifndef STMT_END
-# define STMT_END while (0)
-#endif
-
-#if SU_DEBUG
-# define SU_D(X) STMT_START X STMT_END
-#else
-# define SU_D(X)
-#endif
-
 #ifndef Newx
 # define Newx(v, n, c) New(0, v, n, c)
 #endif
@@ -72,7 +58,7 @@
 #endif
 
 #ifndef newSV_type
-STATIC SV *su_newSV_type(pTHX_ svtype t) {
+static SV *su_newSV_type(pTHX_ svtype t) {
  SV *sv = newSV(0);
  SvUPGRADE(sv, t);
  return sv;
@@ -80,6 +66,13 @@ STATIC SV *su_newSV_type(pTHX_ svtype t) {
 # define newSV_type(T) su_newSV_type(aTHX_ (T))
 #endif
 
+#ifdef newSVpvn_flags
+# define su_newmortal_pvn(S, L) newSVpvn_flags((S), (L), SVs_TEMP)
+#else
+# define su_newmortal_pvn(S, L) sv_2mortal(newSVpvn((S), (L)))
+#endif
+#define su_newmortal_pvs(S) su_newmortal_pvn((S), sizeof(S)-1)
+
 #ifndef SvPV_const
 # define SvPV_const(S, L) SvPV(S, L)
 #endif
@@ -116,18 +109,88 @@ STATIC SV *su_newSV_type(pTHX_ svtype t) {
 # define CvISXSUB(C) CvXSUB(C)
 #endif
 
+#ifndef PadlistARRAY
+# define PadlistARRAY(P) AvARRAY(P)
+# define PadARRAY(P)     AvARRAY(P)
+#endif
+
 #ifndef CxHASARGS
 # define CxHASARGS(C) ((C)->blk_sub.hasargs)
 #endif
 
+#ifndef CxGIMME
+# ifdef G_WANT
+#  define CxGIMME(C) ((C)->blk_gimme & G_WANT)
+# else
+#  define CxGIMME(C) ((C)->blk_gimme)
+# endif
+#endif
+
+#ifndef CxOLD_OP_TYPE
+# define CxOLD_OP_TYPE(C) (C)->blk_eval.old_op_type
+#endif
+
+#ifndef OutCopFILE
+# define OutCopFILE(C) CopFILE(C)
+#endif
+
+#ifndef OutCopFILE_len
+# define OutCopFILE_len(C) strlen(OutCopFILE(C))
+#endif
+
+#ifndef CopHINTS_get
+# define CopHINTS_get(C) ((I32) (C)->op_private & HINT_PRIVATE_MASK)
+#endif
+
+#ifndef CopHINTHASH_get
+# define CopHINTHASH_get(C) (C)->cop_hints_hash
+#endif
+
+#ifndef cophh_2hv
+# define COPHH           struct refcounted_he
+# define cophh_2hv(H, F) Perl_refcounted_he_chain_2hv(aTHX_ (H))
+#endif
+
 #ifndef HvNAME_get
 # define HvNAME_get(H) HvNAME(H)
 #endif
 
+#ifndef HvNAMELEN
+# define HvNAMELEN(H) strlen(HvNAME(H))
+#endif
+
 #ifndef gv_fetchpvn_flags
 # define gv_fetchpvn_flags(A, B, C, D) gv_fetchpv((A), (C), (D))
 #endif
 
+#ifndef hv_fetchs
+# define hv_fetchs(H, K, L) hv_fetch((H), (K), sizeof(K)-1, (L))
+#endif
+
+#ifndef OP_GIMME_REVERSE
+static U8 su_op_gimme_reverse(U8 gimme) {
+ switch (gimme) {
+  case G_VOID:
+   return OPf_WANT_VOID;
+  case G_ARRAY:
+   return OPf_WANT_LIST;
+  default:
+   break;
+ }
+
+ return OPf_WANT_SCALAR;
+}
+#define OP_GIMME_REVERSE(G) su_op_gimme_reverse(G)
+#endif
+
+#ifndef OpSIBLING
+# ifdef OP_SIBLING
+#  define OpSIBLING(O) OP_SIBLING(O)
+# else
+#  define OpSIBLING(O) ((O)->op_sibling)
+# endif
+#endif
+
 #ifndef PERL_MAGIC_tied
 # define PERL_MAGIC_tied 'P'
 #endif
@@ -140,44 +203,144 @@ STATIC SV *su_newSV_type(pTHX_ svtype t) {
 # define NEGATIVE_INDICES_VAR "NEGATIVE_INDICES"
 #endif
 
-#define SU_HAS_PERL(R, V, S) (PERL_REVISION > (R) || (PERL_REVISION == (R) && (PERL_VERSION > (V) || (PERL_VERSION == (V) && (PERL_SUBVERSION >= (S))))))
-#define SU_HAS_PERL_EXACT(R, V, S) ((PERL_REVISION == (R)) && (PERL_VERSION == (V)) && (PERL_SUBVERSION == (S)))
+/* CX_ARGARRAY(cx): the AV at pad[0] of the CV associated with CXt_SUB
+ * context cx */
+
+#if XSH_HAS_PERL(5, 23, 8)
+# define CX_ARGARRAY(cx) \
+    ((AV*)(AvARRAY(MUTABLE_AV(                     \
+        PadlistARRAY(CvPADLIST(cx->blk_sub.cv))[   \
+            CvDEPTH(cx->blk_sub.cv)]))[0]))
+/* XXX is the new def ok to use in lvalue cxt? Formerly it assigned to
+ * blk_sub.argarray, now to pad[0]. Does this matter?
+ */
+# define CX_ARGARRAY_set(cx,ary) \
+    (AvARRAY(MUTABLE_AV(                     \
+        PadlistARRAY(CvPADLIST(cx->blk_sub.cv))[   \
+            CvDEPTH(cx->blk_sub.cv)]))[0] = (SV*)(ary))
+#else
+# define CX_ARGARRAY(cx)         (cx->blk_sub.argarray)
+# define CX_ARGARRAY_set(cx,ary) (cx->blk_sub.argarray = (ary))
+#endif
+
 
-/* --- Threads and multiplicity -------------------------------------------- */
+/* --- Error messages ------------------------------------------------------ */
 
-#ifndef SU_MULTIPLICITY
-# if defined(MULTIPLICITY) || defined(PERL_IMPLICIT_CONTEXT)
-#  define SU_MULTIPLICITY 1
-# else
-#  define SU_MULTIPLICITY 0
-# endif
-#endif
-#if SU_MULTIPLICITY && !defined(tTHX)
-# define tTHX PerlInterpreter*
-#endif
+static const char su_stack_smash[]    = "Cannot target a scope outside of the current stack";
+static const char su_no_such_target[] = "No targetable %s scope in the current stack";
 
-#if SU_MULTIPLICITY && defined(USE_ITHREADS) && defined(dMY_CXT) && defined(MY_CXT) && defined(START_MY_CXT) && defined(MY_CXT_INIT) && (defined(MY_CXT_CLONE) || defined(dMY_CXT_SV))
-# define SU_THREADSAFE 1
-# ifndef MY_CXT_CLONE
-#  define MY_CXT_CLONE \
-    dMY_CXT_SV;                                                      \
-    my_cxt_t *my_cxtp = (my_cxt_t*)SvPVX(newSV(sizeof(my_cxt_t)-1)); \
-    Copy(INT2PTR(my_cxt_t*, SvUV(my_cxt_sv)), my_cxtp, 1, my_cxt_t); \
-    sv_setuv(my_cxt_sv, PTR2UV(my_cxtp))
-# endif
-#else
-# define SU_THREADSAFE 0
-# undef  dMY_CXT
-# define dMY_CXT      dNOOP
-# undef  MY_CXT
-# define MY_CXT       su_globaldata
-# undef  START_MY_CXT
-# define START_MY_CXT STATIC my_cxt_t MY_CXT;
-# undef  MY_CXT_INIT
-# define MY_CXT_INIT  NOOP
-# undef  MY_CXT_CLONE
-# define MY_CXT_CLONE NOOP
-#endif
+/* --- Unique context ID global storage ------------------------------------ */
+
+/* ... Sequence ID counter ................................................. */
+
+typedef struct {
+ UV     *seqs;
+ STRLEN  size;
+} su_uv_array;
+
+static su_uv_array su_uid_seq_counter;
+
+#ifdef USE_ITHREADS
+
+static perl_mutex su_uid_seq_counter_mutex;
+
+#endif /* USE_ITHREADS */
+
+static UV su_uid_seq_next(pTHX_ UV depth) {
+#define su_uid_seq_next(D) su_uid_seq_next(aTHX_ (D))
+ UV seq;
+ UV *seqs;
+
+ XSH_LOCK(&su_uid_seq_counter_mutex);
+
+ seqs = su_uid_seq_counter.seqs;
+
+ if (depth >= su_uid_seq_counter.size) {
+  UV i;
+
+  seqs = PerlMemShared_realloc(seqs, (depth + 1) * sizeof(UV));
+  for (i = su_uid_seq_counter.size; i <= depth; ++i)
+   seqs[i] = 0;
+
+  su_uid_seq_counter.seqs = seqs;
+  su_uid_seq_counter.size = depth + 1;
+ }
+
+ seq = ++seqs[depth];
+
+ XSH_UNLOCK(&su_uid_seq_counter_mutex);
+
+ return seq;
+}
+
+/* ... UID storage ......................................................... */
+
+typedef struct {
+ UV  seq;
+ U32 flags;
+} su_uid;
+
+#define SU_UID_ACTIVE 1
+
+static UV su_uid_depth(pTHX_ I32 cxix) {
+#define su_uid_depth(I) su_uid_depth(aTHX_ (I))
+ const PERL_SI *si;
+ UV depth;
+
+ depth = cxix;
+ for (si = PL_curstackinfo->si_prev; si; si = si->si_prev)
+  depth += si->si_cxix + 1;
+
+ return depth;
+}
+
+typedef struct {
+ su_uid *map;
+ STRLEN  used;
+ STRLEN  alloc;
+} su_uid_storage;
+
+static void su_uid_storage_dup(pTHX_ su_uid_storage *new_cxt, const su_uid_storage *old_cxt, UV max_depth) {
+#define su_uid_storage_dup(N, O, D) su_uid_storage_dup(aTHX_ (N), (O), (D))
+ su_uid *old_map = old_cxt->map;
+
+ if (old_map) {
+  su_uid *new_map  = new_cxt->map;
+  STRLEN  old_used = old_cxt->used;
+  STRLEN  new_used, new_alloc;
+  STRLEN  i;
+
+  new_used      = max_depth < old_used ? max_depth : old_used;
+  new_cxt->used = new_used;
+
+  if (new_used <= new_cxt->alloc) {
+   new_alloc      = new_cxt->alloc;
+  } else {
+   new_alloc      = new_used;
+   Renew(new_map, new_alloc, su_uid);
+   new_cxt->map   = new_map;
+   new_cxt->alloc = new_alloc;
+  }
+
+  for (i = 0; i < new_alloc; ++i) {
+   su_uid *new_uid = new_map + i;
+
+   if (i < new_used) { /* => i < max_depth && i < old_used */
+    su_uid *old_uid = old_map + i;
+
+    if (old_uid && (old_uid->flags & SU_UID_ACTIVE)) {
+     *new_uid = *old_uid;
+     continue;
+    }
+   }
+
+   new_uid->seq   = 0;
+   new_uid->flags = 0;
+  }
+ }
+
+ return;
+}
 
 /* --- unwind() global storage --------------------------------------------- */
 
@@ -189,36 +352,50 @@ typedef struct {
  OP       proxy_op;
 } su_unwind_storage;
 
+/* --- yield() global storage ---------------------------------------------- */
+
+typedef struct {
+ I32      cxix;
+ I32      items;
+ SV     **savesp;
+ UNOP     leave_op;
+ OP       proxy_op;
+} su_yield_storage;
+
 /* --- uplevel() data tokens and global storage ---------------------------- */
 
-#define SU_UPLEVEL_HIJACKS_RUNOPS SU_HAS_PERL(5, 8, 0)
+#define SU_UPLEVEL_HIJACKS_RUNOPS XSH_HAS_PERL(5, 8, 0)
 
 typedef struct {
- void *next;
+ void          *next;
 
- I32  cxix;
- bool died;
+ su_uid_storage tmp_uid_storage;
+ su_uid_storage old_uid_storage;
 
- CV  *target;
- I32  target_depth;
+ I32            cxix;
 
- CV  *callback;
- CV  *renamed;
+ I32            target_depth;
+ CV            *target;
 
- PERL_SI *si;
- PERL_SI *old_curstackinfo;
- AV      *old_mainstack;
+ CV            *callback;
+ CV            *renamed;
+
+ PERL_SI       *si;
+ PERL_SI       *old_curstackinfo;
+ AV            *old_mainstack;
 
- COP *old_curcop;
+ COP           *old_curcop;
 
+ OP            *old_op;
 #if SU_UPLEVEL_HIJACKS_RUNOPS
  runops_proc_t  old_runops;
 #endif
  bool           old_catch;
- OP            *old_op;
+
+ bool           died;
 } su_uplevel_ud;
 
-STATIC su_uplevel_ud *su_uplevel_ud_new(pTHX) {
+static su_uplevel_ud *su_uplevel_ud_new(pTHX) {
 #define su_uplevel_ud_new() su_uplevel_ud_new(aTHX)
  su_uplevel_ud *sud;
  PERL_SI       *si;
@@ -226,24 +403,31 @@ STATIC su_uplevel_ud *su_uplevel_ud_new(pTHX) {
  Newx(sud, 1, su_uplevel_ud);
  sud->next = NULL;
 
+ sud->tmp_uid_storage.map   = NULL;
+ sud->tmp_uid_storage.used  = 0;
+ sud->tmp_uid_storage.alloc = 0;
+
  Newx(si, 1, PERL_SI);
  si->si_stack   = newAV();
  AvREAL_off(si->si_stack);
  si->si_cxstack = NULL;
- si->si_cxmax   = 0;
+ si->si_cxmax   = -1;
 
  sud->si = si;
 
  return sud;
 }
 
-STATIC void su_uplevel_ud_delete(pTHX_ su_uplevel_ud *sud) {
+static void su_uplevel_ud_delete(pTHX_ su_uplevel_ud *sud) {
 #define su_uplevel_ud_delete(S) su_uplevel_ud_delete(aTHX_ (S))
  PERL_SI *si = sud->si;
 
  Safefree(si->si_cxstack);
  SvREFCNT_dec(si->si_stack);
  Safefree(si);
+
+ Safefree(sud->tmp_uid_storage.map);
+
  Safefree(sud);
 
  return;
@@ -261,19 +445,42 @@ typedef struct {
 
 /* --- Global data --------------------------------------------------------- */
 
-#define MY_CXT_KEY __PACKAGE__ "::_guts" XS_VERSION
-
 typedef struct {
  char               *stack_placeholder;
  su_unwind_storage   unwind_storage;
+ su_yield_storage    yield_storage;
  su_uplevel_storage  uplevel_storage;
-} my_cxt_t;
+ su_uid_storage      uid_storage;
+} xsh_user_cxt_t;
+
+#define XSH_THREADS_USER_CONTEXT            1
+#define XSH_THREADS_USER_CLONE_NEEDS_DUP    0
+#define XSH_THREADS_COMPILE_TIME_PROTECTION 0
 
-START_MY_CXT
+#if XSH_THREADSAFE
+
+static void xsh_user_clone(pTHX_ const xsh_user_cxt_t *old_cxt, xsh_user_cxt_t *new_cxt) {
+ new_cxt->uplevel_storage.top   = NULL;
+ new_cxt->uplevel_storage.root  = NULL;
+ new_cxt->uplevel_storage.count = 0;
+
+ new_cxt->uid_storage.map   = NULL;
+ new_cxt->uid_storage.used  = 0;
+ new_cxt->uid_storage.alloc = 0;
+
+ su_uid_storage_dup(&new_cxt->uid_storage, &old_cxt->uid_storage,
+                    old_cxt->uid_storage.used);
+
+ return;
+}
+
+#endif /* XSH_THREADSAFE */
+
+#include "xsh/threads.h"
 
 /* --- Stack manipulations ------------------------------------------------- */
 
-#define SU_SAVE_PLACEHOLDER() save_pptr(&MY_CXT.stack_placeholder)
+#define SU_SAVE_PLACEHOLDER() save_pptr(&XSH_CXT.stack_placeholder)
 
 #define SU_SAVE_DESTRUCTOR_SIZE  3
 #define SU_SAVE_PLACEHOLDER_SIZE 3
@@ -304,11 +511,11 @@ START_MY_CXT
 
 #define SU_SAVE_GVCV_SIZE SU_SAVE_DESTRUCTOR_SIZE
 
-#if !SU_HAS_PERL(5, 8, 9)
+#if !XSH_HAS_PERL(5, 8, 9)
 # define SU_SAVE_GP_SIZE 6
-#elif !SU_HAS_PERL(5, 13, 0) || (SU_RELEASE && SU_HAS_PERL_EXACT(5, 13, 0))
+#elif !XSH_HAS_PERL(5, 13, 0) || (SU_RELEASE && XSH_HAS_PERL_EXACT(5, 13, 0))
 # define SU_SAVE_GP_SIZE 3
-#elif !SU_HAS_PERL(5, 13, 8)
+#elif !XSH_HAS_PERL(5, 13, 8)
 # define SU_SAVE_GP_SIZE 4
 #else
 # define SU_SAVE_GP_SIZE 3
@@ -327,7 +534,7 @@ START_MY_CXT
 
 /* ... Saving array elements ............................................... */
 
-STATIC I32 su_av_key2idx(pTHX_ AV *av, I32 key) {
+static I32 su_av_key2idx(pTHX_ AV *av, I32 key) {
 #define su_av_key2idx(A, K) su_av_key2idx(aTHX_ (A), (K))
  I32 idx;
 
@@ -335,13 +542,14 @@ STATIC I32 su_av_key2idx(pTHX_ AV *av, I32 key) {
   return key;
 
 /* Added by MJD in perl-5.8.1 with 6f12eb6d2a1dfaf441504d869b27d2e40ef4966a */
-#if SU_HAS_PERL(5, 8, 1)
+#if XSH_HAS_PERL(5, 8, 1)
  if (SvRMAGICAL(av)) {
   const MAGIC * const tied_magic = mg_find((SV *) av, PERL_MAGIC_tied);
   if (tied_magic) {
-   SV * const * const negative_indices_glob =
-                    hv_fetch(SvSTASH(SvRV(SvTIED_obj((SV *) (av), tied_magic))),
-                             NEGATIVE_INDICES_VAR, 16, 0);
+   SV * const * const negative_indices_glob = hv_fetch(
+    SvSTASH(SvRV(SvTIED_obj((SV *) (av), tied_magic))),
+    NEGATIVE_INDICES_VAR, sizeof(NEGATIVE_INDICES_VAR)-1, 0
+   );
    if (negative_indices_glob && SvTRUE(GvSV(*negative_indices_glob)))
     return key;
   }
@@ -362,7 +570,7 @@ typedef struct {
  I32 idx;
 } su_ud_adelete;
 
-STATIC void su_adelete(pTHX_ void *ud_) {
+static void su_adelete(pTHX_ void *ud_) {
  su_ud_adelete *ud = (su_ud_adelete *) ud_;
 
  av_delete(ud->av, ud->idx, G_DISCARD);
@@ -371,7 +579,7 @@ STATIC void su_adelete(pTHX_ void *ud_) {
  Safefree(ud);
 }
 
-STATIC void su_save_adelete(pTHX_ AV *av, I32 idx) {
+static void su_save_adelete(pTHX_ AV *av, I32 idx) {
 #define su_save_adelete(A, K) su_save_adelete(aTHX_ (A), (K))
  su_ud_adelete *ud;
 
@@ -387,7 +595,7 @@ STATIC void su_save_adelete(pTHX_ AV *av, I32 idx) {
 
 #endif /* SAVEADELETE */
 
-STATIC void su_save_aelem(pTHX_ AV *av, SV *key, SV *val) {
+static void su_save_aelem(pTHX_ AV *av, SV *key, SV *val) {
 #define su_save_aelem(A, K, V) su_save_aelem(aTHX_ (A), (K), (V))
  I32 idx;
  I32 preeminent = 1;
@@ -417,7 +625,7 @@ STATIC void su_save_aelem(pTHX_ AV *av, SV *key, SV *val) {
 
 /* ... Saving hash elements ................................................ */
 
-STATIC void su_save_helem(pTHX_ HV *hv, SV *keysv, SV *val) {
+static void su_save_helem(pTHX_ HV *hv, SV *keysv, SV *val) {
 #define su_save_helem(H, K, V) su_save_helem(aTHX_ (H), (K), (V))
  I32 preeminent = 1;
  HE *he;
@@ -455,7 +663,7 @@ STATIC void su_save_helem(pTHX_ HV *hv, SV *keysv, SV *val) {
 
 /* ... Saving code slots from a glob ....................................... */
 
-#if !SU_HAS_PERL(5, 10, 0) && !defined(mro_method_changed_in)
+#if !XSH_HAS_PERL(5, 10, 0) && !defined(mro_method_changed_in)
 # define mro_method_changed_in(G) PL_sub_generation++
 #endif
 
@@ -464,7 +672,7 @@ typedef struct {
  CV *old_cv;
 } su_save_gvcv_ud;
 
-STATIC void su_restore_gvcv(pTHX_ void *ud_) {
+static void su_restore_gvcv(pTHX_ void *ud_) {
  su_save_gvcv_ud *ud = ud_;
  GV              *gv = ud->gv;
 
@@ -475,7 +683,7 @@ STATIC void su_restore_gvcv(pTHX_ void *ud_) {
  Safefree(ud);
 }
 
-STATIC void su_save_gvcv(pTHX_ GV *gv) {
+static void su_save_gvcv(pTHX_ GV *gv) {
 #define su_save_gvcv(G) su_save_gvcv(aTHX_ (G))
  su_save_gvcv_ud *ud;
 
@@ -493,16 +701,23 @@ STATIC void su_save_gvcv(pTHX_ GV *gv) {
 /* --- Actions ------------------------------------------------------------- */
 
 typedef struct {
- I32 depth;
- I32 pad;
+ U8   type;
+ U8   private;
+ U8   pad;
+ /* spare */
+ I32  depth;
  I32 *origin;
- void (*handler)(pTHX_ void *);
 } su_ud_common;
 
-#define SU_UD_DEPTH(U)   (((su_ud_common *) (U))->depth)
+#define SU_UD_TYPE(U)    (((su_ud_common *) (U))->type)
+#define SU_UD_PRIVATE(U) (((su_ud_common *) (U))->private)
 #define SU_UD_PAD(U)     (((su_ud_common *) (U))->pad)
+#define SU_UD_DEPTH(U)   (((su_ud_common *) (U))->depth)
 #define SU_UD_ORIGIN(U)  (((su_ud_common *) (U))->origin)
-#define SU_UD_HANDLER(U) (((su_ud_common *) (U))->handler)
+
+#define SU_UD_TYPE_REAP     0
+#define SU_UD_TYPE_LOCALIZE 1
+#define SU_UD_TYPE_UID      2
 
 #define SU_UD_FREE(U) STMT_START { \
  if (SU_UD_ORIGIN(U)) Safefree(SU_UD_ORIGIN(U)); \
@@ -511,25 +726,25 @@ typedef struct {
 
 /* ... Reap ................................................................ */
 
+#define SU_SAVE_LAST_CX (!XSH_HAS_PERL(5, 8, 4) || (XSH_HAS_PERL(5, 9, 5) && !XSH_HAS_PERL(5, 14, 0)) || XSH_HAS_PERL(5, 15, 0))
+
 typedef struct {
  su_ud_common ci;
- SV *cb;
+ SV          *cb;
 } su_ud_reap;
 
-STATIC void su_call(pTHX_ void *ud_) {
- su_ud_reap *ud = (su_ud_reap *) ud_;
-#if SU_HAS_PERL(5, 9, 5)
- PERL_CONTEXT saved_cx;
+#define SU_UD_REAP_CB(U) (((su_ud_reap *) (U))->cb)
+
+static void su_call(pTHX_ SV *cb) {
+#if SU_SAVE_LAST_CX
  I32 cxix;
-#endif
+ PERL_CONTEXT saved_cx;
+#endif /* SU_SAVE_LAST_CX */
 
  dSP;
 
- SU_D({
-  PerlIO_printf(Perl_debug_log,
-                "%p: @@@ call\n%p: depth=%2d scope_ix=%2d save_ix=%2d\n",
-                 ud, ud, SU_UD_DEPTH(ud), PL_scopestack_ix, PL_savestack_ix);
- });
+ XSH_D(su_debug_log("@@@ call scope_ix=%2d save_ix=%2d\n",
+                          PL_scopestack_ix, PL_savestack_ix));
 
  ENTER;
  SAVETMPS;
@@ -537,61 +752,50 @@ STATIC void su_call(pTHX_ void *ud_) {
  PUSHMARK(SP);
  PUTBACK;
 
+#if SU_SAVE_LAST_CX
  /* If the recently popped context isn't saved there, it will be overwritten by
   * the sub scope from call_sv, although it's still needed in our caller. */
-
-#if SU_HAS_PERL(5, 9, 5)
- if (cxstack_ix < cxstack_max)
-  cxix = cxstack_ix + 1;
- else
-  cxix = Perl_cxinc(aTHX);
+ cxix     = (cxstack_ix < cxstack_max) ? (cxstack_ix + 1) : Perl_cxinc(aTHX);
  saved_cx = cxstack[cxix];
-#endif
+#endif /* SU_SAVE_LAST_CX */
 
- call_sv(ud->cb, G_VOID);
+ call_sv(cb, G_VOID);
 
-#if SU_HAS_PERL(5, 9, 5)
+#if SU_SAVE_LAST_CX
  cxstack[cxix] = saved_cx;
-#endif
+#endif /* SU_SAVE_LAST_CX */
 
  PUTBACK;
 
  FREETMPS;
  LEAVE;
 
- SvREFCNT_dec(ud->cb);
- SU_UD_FREE(ud);
-}
-
-STATIC void su_reap(pTHX_ void *ud) {
-#define su_reap(U) su_reap(aTHX_ (U))
- SU_D({
-  PerlIO_printf(Perl_debug_log,
-                "%p: === reap\n%p: depth=%2d scope_ix=%2d save_ix=%2d\n",
-                 ud, ud, SU_UD_DEPTH(ud), PL_scopestack_ix, PL_savestack_ix);
- });
+ SvREFCNT_dec(cb);
 
- SAVEDESTRUCTOR_X(su_call, ud);
+ return;
 }
 
 /* ... Localize & localize array/hash element .............................. */
 
 typedef struct {
  su_ud_common ci;
- SV    *sv;
- SV    *val;
- SV    *elem;
- svtype type;
+ SV          *sv;
+ SV          *val;
+ SV          *elem;
 } su_ud_localize;
 
+#define SU_UD_LOCALIZE_SV(U)   (((su_ud_localize *) (U))->sv)
+#define SU_UD_LOCALIZE_VAL(U)  (((su_ud_localize *) (U))->val)
+#define SU_UD_LOCALIZE_ELEM(U) (((su_ud_localize *) (U))->elem)
+
 #define SU_UD_LOCALIZE_FREE(U) STMT_START { \
- SvREFCNT_dec((U)->elem); \
- SvREFCNT_dec((U)->val);  \
- SvREFCNT_dec((U)->sv);   \
- SU_UD_FREE(U);           \
+ SvREFCNT_dec(SU_UD_LOCALIZE_ELEM(U)); \
+ SvREFCNT_dec(SU_UD_LOCALIZE_VAL(U)); \
+ SvREFCNT_dec(SU_UD_LOCALIZE_SV(U)); \
+ SU_UD_FREE(U); \
 } STMT_END
 
-STATIC I32 su_ud_localize_init(pTHX_ su_ud_localize *ud, SV *sv, SV *val, SV *elem) {
+static I32 su_ud_localize_init(pTHX_ su_ud_localize *ud, SV *sv, SV *val, SV *elem) {
 #define su_ud_localize_init(UD, S, V, E) su_ud_localize_init(aTHX_ (UD), (S), (V), (E))
  UV deref = 0;
  svtype t = SVt_NULL;
@@ -664,21 +868,22 @@ STATIC I32 su_ud_localize_init(pTHX_ su_ud_localize *ud, SV *sv, SV *val, SV *el
  }
  /* When deref is set, val isn't NULL */
 
+ SU_UD_PRIVATE(ud) = t;
+
  ud->sv   = sv;
  ud->val  = val ? newSVsv(deref ? SvRV(val) : val) : NULL;
  ud->elem = SvREFCNT_inc(elem);
- ud->type = t;
 
  return size;
 }
 
-STATIC void su_localize(pTHX_ void *ud_) {
+static void su_localize(pTHX_ void *ud_) {
 #define su_localize(U) su_localize(aTHX_ (U))
  su_ud_localize *ud = (su_ud_localize *) ud_;
  SV *sv   = ud->sv;
  SV *val  = ud->val;
  SV *elem = ud->elem;
- svtype t = ud->type;
+ svtype t = SU_UD_PRIVATE(ud);
  GV *gv;
 
  if (SvTYPE(sv) >= SVt_PVGV) {
@@ -693,13 +898,12 @@ STATIC void su_localize(pTHX_ void *ud_) {
 #endif
  }
 
- SU_D({
+ XSH_D({
   SV *z = newSV(0);
   SvUPGRADE(z, t);
-  PerlIO_printf(Perl_debug_log, "%p: === localize a %s\n",ud, sv_reftype(z, 0));
-  PerlIO_printf(Perl_debug_log,
-                "%p: depth=%2d scope_ix=%2d save_ix=%2d\n",
-                 ud, SU_UD_DEPTH(ud), PL_scopestack_ix, PL_savestack_ix);
+  su_debug_log("%p: === localize a %s\n",ud, sv_reftype(z, 0));
+  su_debug_log("%p: depth=%2d scope_ix=%2d save_ix=%2d\n",
+                ud, SU_UD_DEPTH(ud), PL_scopestack_ix, PL_savestack_ix);
   SvREFCNT_dec(z);
  });
 
@@ -708,14 +912,14 @@ STATIC void su_localize(pTHX_ void *ud_) {
   case SVt_PVAV:
    if (elem) {
     su_save_aelem(GvAV(gv), elem, val);
-    goto done;
+    return;
    } else
     save_ary(gv);
    break;
   case SVt_PVHV:
    if (elem) {
     su_save_helem(GvHV(gv), elem, val);
-    goto done;
+    return;
    } else
     save_hash(gv);
    break;
@@ -733,170 +937,244 @@ STATIC void su_localize(pTHX_ void *ud_) {
  if (val)
   SvSetMagicSV((SV *) gv, val);
 
-done:
- SU_UD_LOCALIZE_FREE(ud);
+ return;
+}
+
+/* ... Unique context ID ................................................... */
+
+/* We must pass the index because XSH_CXT.uid_storage might be reallocated
+ * between the UID fetch and the invalidation at the end of scope. */
+
+typedef struct {
+ su_ud_common ci;
+ I32          idx;
+} su_ud_uid;
+
+static void su_uid_drop(pTHX_ void *ud_) {
+ su_ud_uid *ud = ud_;
+ dXSH_CXT;
+
+ XSH_CXT.uid_storage.map[ud->idx].flags &= ~SU_UID_ACTIVE;
+
+ SU_UD_FREE(ud);
+
+ return;
 }
 
 /* --- Pop a context back -------------------------------------------------- */
 
-#if SU_DEBUG
-# ifdef DEBUGGING
-#  define SU_CXNAME PL_block_type[CxTYPE(&cxstack[cxstack_ix])]
+#ifdef DEBUGGING
+# define SU_CXNAME(C) PL_block_type[CxTYPE(C)]
+#else
+# if XSH_HAS_PERL(5, 11, 0)
+static const char *su_block_type[] = {
+ "NULL",
+ "WHEN",
+ "BLOCK",
+ "GIVEN",
+ "LOOP_FOR",
+ "LOOP_PLAIN",
+ "LOOP_LAZYSV",
+ "LOOP_LAZYIV",
+ "SUB",
+ "FORMAT",
+ "EVAL",
+ "SUBST"
+};
+# elif XSH_HAS_PERL(5, 9, 3)
+static const char *su_block_type[] = {
+ "NULL",
+ "SUB",
+ "EVAL",
+ "WHEN",
+ "SUBST",
+ "BLOCK",
+ "FORMAT",
+ "GIVEN",
+ "LOOP_FOR",
+ "LOOP_PLAIN",
+ "LOOP_LAZYSV",
+ "LOOP_LAZYIV"
+};
 # else
-#  define SU_CXNAME "XXX"
+static const char *su_block_type[] = {
+ "NULL",
+ "SUB",
+ "EVAL",
+ "LOOP",
+ "SUBST",
+ "BLOCK"
+};
 # endif
+# define SU_CXNAME(C) su_block_type[CxTYPE(C)]
 #endif
 
-STATIC void su_pop(pTHX_ void *ud) {
+static void su_pop(pTHX_ void *ud) {
 #define su_pop(U) su_pop(aTHX_ (U))
  I32 depth, base, mark, *origin;
  depth = SU_UD_DEPTH(ud);
 
- SU_D(
-  PerlIO_printf(Perl_debug_log,
-   "%p: --- pop a %s\n"
-   "%p: leave scope     at depth=%2d scope_ix=%2d cur_top=%2d cur_base=%2d\n",
-    ud, SU_CXNAME,
-    ud, depth, PL_scopestack_ix,PL_savestack_ix,PL_scopestack[PL_scopestack_ix])
- );
+ XSH_D(su_debug_log(
+  "%p: --- pop a %s\n"
+  "%p: leave scope     at depth=%2d scope_ix=%2d cur_top=%2d cur_base=%2d\n",
+   ud, SU_CXNAME(cxstack + cxstack_ix),
+   ud, depth, PL_scopestack_ix,PL_savestack_ix,PL_scopestack[PL_scopestack_ix]
+ ));
 
  origin = SU_UD_ORIGIN(ud);
  mark   = origin[depth];
  base   = origin[depth - 1];
 
- SU_D(PerlIO_printf(Perl_debug_log,
-                    "%p: original scope was %*c top=%2d     base=%2d\n",
+ XSH_D(su_debug_log("%p: original scope was %*c top=%2d     base=%2d\n",
                      ud,                24, ' ',    mark,        base));
 
  if (base < mark) {
-  SU_D(PerlIO_printf(Perl_debug_log, "%p: clear leftovers\n", ud));
+#if XSH_HAS_PERL(5, 19, 4)
+  I32 save = -1;
+  PERL_CONTEXT *cx;
+#endif
+
+  XSH_D(su_debug_log("%p: clear leftovers\n", ud));
+
+#if XSH_HAS_PERL(5, 19, 4)
+  cx = cxstack + cxstack_ix;
+  if (CxTYPE(cx) == CXt_SUB || CxTYPE(cx) == CXt_FORMAT)
+   save = PL_scopestack[cx->blk_oldscopesp - 1];
+#endif
+
   PL_savestack_ix = mark;
   leave_scope(base);
+
+#if XSH_HAS_PERL(5, 19, 4)
+  if (CxTYPE(cx) == CXt_SUB || CxTYPE(cx) == CXt_FORMAT)
+   PL_scopestack[cx->blk_oldscopesp - 1] = save;
+#endif
  }
  PL_savestack_ix = base;
 
  SU_UD_DEPTH(ud) = --depth;
 
  if (depth > 0) {
-  I32 pad;
+  U8 pad;
 
-  if ((pad = SU_UD_PAD(ud))) {
-   dMY_CXT;
+  if ((pad = SU_UD_PAD(ud)) > 0) {
+   dXSH_CXT;
    do {
-    SU_D(PerlIO_printf(Perl_debug_log,
+    XSH_D(su_debug_log(
           "%p: push a pad slot at depth=%2d scope_ix=%2d save_ix=%2d\n",
            ud,                       depth, PL_scopestack_ix, PL_savestack_ix));
     SU_SAVE_PLACEHOLDER();
    } while (--pad);
   }
 
-  SU_D(PerlIO_printf(Perl_debug_log,
-          "%p: push destructor at depth=%2d scope_ix=%2d save_ix=%2d\n",
-           ud,                       depth, PL_scopestack_ix, PL_savestack_ix));
+  XSH_D(su_debug_log(
+        "%p: push destructor at depth=%2d scope_ix=%2d save_ix=%2d\n",
+         ud,                        depth, PL_scopestack_ix, PL_savestack_ix));
   SAVEDESTRUCTOR_X(su_pop, ud);
  } else {
-  SU_UD_HANDLER(ud)(aTHX_ ud);
+  switch (SU_UD_TYPE(ud)) {
+   case SU_UD_TYPE_REAP: {
+    XSH_D(su_debug_log("%p: === reap\n%p: depth=%2d scope_ix=%2d save_ix=%2d\n",
+                   ud, ud, SU_UD_DEPTH(ud), PL_scopestack_ix, PL_savestack_ix));
+    SAVEDESTRUCTOR_X(su_call, SU_UD_REAP_CB(ud));
+    SU_UD_FREE(ud);
+    break;
+   }
+   case SU_UD_TYPE_LOCALIZE:
+    su_localize(ud);
+    SU_UD_LOCALIZE_FREE(ud);
+    break;
+   case SU_UD_TYPE_UID:
+    SAVEDESTRUCTOR_X(su_uid_drop, ud);
+    break;
+  }
  }
 
- SU_D(PerlIO_printf(Perl_debug_log,
-                    "%p: --- end pop: cur_top=%2d == cur_base=%2d\n",
+ XSH_D(su_debug_log("%p: --- end pop: cur_top=%2d == cur_base=%2d\n",
                      ud, PL_savestack_ix, PL_scopestack[PL_scopestack_ix]));
 }
 
 /* --- Initialize the stack and the action userdata ------------------------ */
 
-STATIC I32 su_init(pTHX_ void *ud, I32 cxix, I32 size) {
+static I32 su_init(pTHX_ void *ud, I32 cxix, I32 size) {
 #define su_init(U, C, S) su_init(aTHX_ (U), (C), (S))
- I32 i, depth = 1, pad, offset, *origin;
-
- SU_D(PerlIO_printf(Perl_debug_log, "%p: ### init for cx %d\n", ud, cxix));
-
- if (size <= SU_SAVE_DESTRUCTOR_SIZE)
+ I32 i, depth, offset, base, *origin;
+ U8 pad;
+
+ XSH_D(su_debug_log("%p: ### init for cx %d\n", ud, cxix));
+
+ /* su_pop() is going to be called from leave_scope(), so before pushing the
+  * next callback, we'll want to flush the current scope stack slice first.
+  * However, if we want the next callback not to be processed immediately by
+  * the current leave_scope(), we'll need to hide it by artificially
+  * incrementing the scope stack marker before. For the intermediate bumps,
+  * we will only need a bump of SU_SAVE_DESTRUCTOR_SIZE items, but for the
+  * last one we will need a bump of size items. However, in order to preserve
+  * the natural ordering between scope stack markers, we cannot bump lower
+  * markers more than higher ones. This is why we bump the intermediate markers
+  * by the smallest multiple of SU_SAVE_PLACEHOLDER_SIZE greater or equal to
+  * max(SU_SAVE_DESTRUCTOR_SIZE, size). */
+
+ if (size <= SU_SAVE_DESTRUCTOR_SIZE) {
   pad = 0;
- else {
+ } else {
   I32 extra = size - SU_SAVE_DESTRUCTOR_SIZE;
   pad = extra / SU_SAVE_PLACEHOLDER_SIZE;
   if (extra % SU_SAVE_PLACEHOLDER_SIZE)
    ++pad;
  }
  offset = SU_SAVE_DESTRUCTOR_SIZE + SU_SAVE_PLACEHOLDER_SIZE * pad;
+ XSH_D(su_debug_log("%p: size=%d pad=%d offset=%d\n", ud, size, pad, offset));
 
- SU_D(PerlIO_printf(Perl_debug_log, "%p: size=%d pad=%d offset=%d\n",
-                                     ud,    size,   pad,   offset));
+ depth = PL_scopestack_ix - cxstack[cxix].blk_oldscopesp;
+ XSH_D(su_debug_log("%p: going down to depth %d\n", ud, depth));
 
- for (i = cxstack_ix; i > cxix; --i) {
-  PERL_CONTEXT *cx = cxstack + i;
-  switch (CxTYPE(cx)) {
-#if SU_HAS_PERL(5, 10, 0)
-   case CXt_BLOCK:
-    SU_D(PerlIO_printf(Perl_debug_log, "%p: cx %d is block\n", ud, i));
-    /* Given and when blocks are actually followed by a simple block, so skip
-     * it if needed. */
-    if (cxix > 0) { /* Implies i > 0 */
-     PERL_CONTEXT *next = cx - 1;
-     if (CxTYPE(next) == CXt_GIVEN || CxTYPE(next) == CXt_WHEN)
-      --cxix;
-    }
-    depth++;
-    break;
-#endif
-#if SU_HAS_PERL(5, 11, 0)
-   case CXt_LOOP_FOR:
-   case CXt_LOOP_PLAIN:
-   case CXt_LOOP_LAZYSV:
-   case CXt_LOOP_LAZYIV:
-#else
-   case CXt_LOOP:
-#endif
-    SU_D(PerlIO_printf(Perl_debug_log, "%p: cx %d is loop\n", ud, i));
-    depth += 2;
-    break;
-   default:
-    SU_D(PerlIO_printf(Perl_debug_log, "%p: cx %d is other\n", ud, i));
-    depth++;
-    break;
-  }
- }
- SU_D(PerlIO_printf(Perl_debug_log, "%p: going down to depth %d\n", ud, depth));
+ /* We need to bump all the intermediary stack markers just in case an
+  * exception is thrown before the target scope is reached. Indeed, in this
+  * case there might be arbitrary many scope frames flushed at the same time,
+  * and since we cannot know in advance whether this will happen or not, we
+  * have to make sure the final frame is protected for the actual action. But
+  * of course, in order to do that, we also need to bump all the previous stack
+  * markers. If not for this, it should have been possible to just bump the two
+  * next frames in su_pop(). */
 
  Newx(origin, depth + 1, I32);
- origin[0] = PL_scopestack[PL_scopestack_ix - depth];
- PL_scopestack[PL_scopestack_ix - depth] += size;
- for (i = depth - 1; i >= 1; --i) {
-  I32 j = PL_scopestack_ix - i;
-  origin[depth - i] = PL_scopestack[j];
+ base = PL_scopestack_ix - depth;
+ origin[0] = PL_scopestack[base];
+ PL_scopestack[base] += size;
+ for (i = 1; i < depth; ++i) {
+  I32 j = i + base;
+  /* origin[depth - i] == PL_scopestack[PL_scopestack_ix - i] */
+  origin[i] = PL_scopestack[j];
   PL_scopestack[j] += offset;
  }
  origin[depth] = PL_savestack_ix;
 
- SU_UD_ORIGIN(ud) = origin;
- SU_UD_DEPTH(ud)  = depth;
  SU_UD_PAD(ud)    = pad;
+ SU_UD_DEPTH(ud)  = depth;
+ SU_UD_ORIGIN(ud) = origin;
 
  /* Make sure the first destructor fires by pushing enough fake slots on the
   * stack. */
  if (PL_savestack_ix + SU_SAVE_DESTRUCTOR_SIZE
                                        <= PL_scopestack[PL_scopestack_ix - 1]) {
-  dMY_CXT;
+  dXSH_CXT;
   do {
-   SU_D(PerlIO_printf(Perl_debug_log,
-                  "%p: push a fake slot      at scope_ix=%2d  save_ix=%2d\n",
-                   ud,                      PL_scopestack_ix, PL_savestack_ix));
+   XSH_D(su_debug_log("%p: push a fake slot      at scope_ix=%2d save_ix=%2d\n",
+                       ud,                  PL_scopestack_ix, PL_savestack_ix));
    SU_SAVE_PLACEHOLDER();
   } while (PL_savestack_ix + SU_SAVE_DESTRUCTOR_SIZE
                                         <= PL_scopestack[PL_scopestack_ix - 1]);
  }
- SU_D(PerlIO_printf(Perl_debug_log,
-                  "%p: push first destructor at scope_ix=%2d  save_ix=%2d\n",
-                   ud,                      PL_scopestack_ix, PL_savestack_ix));
+ XSH_D(su_debug_log("%p: push first destructor at scope_ix=%2d save_ix=%2d\n",
+                     ud,                    PL_scopestack_ix, PL_savestack_ix));
  SAVEDESTRUCTOR_X(su_pop, ud);
 
- SU_D({
+ XSH_D({
   for (i = 0; i <= depth; ++i) {
    I32 j = PL_scopestack_ix  - i;
-   PerlIO_printf(Perl_debug_log,
-                 "%p: depth=%2d scope_ix=%2d saved_floor=%2d new_floor=%2d\n",
-                  ud,        i, j, origin[depth - i],
+   su_debug_log("%p: depth=%2d scope_ix=%2d saved_floor=%2d new_floor=%2d\n",
+                 ud,         i,           j, origin[depth - i],
                                    i == 0 ? PL_savestack_ix : PL_scopestack[j]);
   }
  });
@@ -906,106 +1184,305 @@ STATIC I32 su_init(pTHX_ void *ud, I32 cxix, I32 size) {
 
 /* --- Unwind stack -------------------------------------------------------- */
 
-STATIC void su_unwind(pTHX_ void *ud_) {
- dMY_CXT;
- I32 cxix    = MY_CXT.unwind_storage.cxix;
- I32 items   = MY_CXT.unwind_storage.items - 1;
- SV **savesp = MY_CXT.unwind_storage.savesp;
+static void su_unwind(pTHX_ void *ud_) {
+ dXSH_CXT;
+ I32 cxix  = XSH_CXT.unwind_storage.cxix;
+ I32 items = XSH_CXT.unwind_storage.items;
  I32 mark;
 
  PERL_UNUSED_VAR(ud_);
 
- if (savesp)
-  PL_stack_sp = savesp;
+ PL_stack_sp = XSH_CXT.unwind_storage.savesp;
+#if XSH_HAS_PERL(5, 19, 4)
+ {
+  I32 i;
+  SV **sp = PL_stack_sp;
+  for (i = -items + 1; i <= 0; ++i)
+   if (!SvTEMP(sp[i]))
+    sv_2mortal(SvREFCNT_inc(sp[i]));
+ }
+#endif
 
  if (cxstack_ix > cxix)
   dounwind(cxix);
 
- /* Hide the level */
- if (items >= 0)
-  PL_stack_sp--;
-
  mark = PL_markstack[cxstack[cxix].blk_oldmarksp];
  *PL_markstack_ptr = PL_stack_sp - PL_stack_base - items;
 
- SU_D({
+ XSH_D({
   I32 gimme = GIMME_V;
-  PerlIO_printf(Perl_debug_log,
-                "%p: cx=%d gimme=%s items=%d sp=%d oldmark=%d mark=%d\n",
-                &MY_CXT, cxix,
+  su_debug_log("%p: cx=%d gimme=%s items=%d sp=%d oldmark=%d mark=%d\n",
+                &XSH_CXT, cxix,
                 gimme == G_VOID ? "void" : gimme == G_ARRAY ? "list" : "scalar",
                 items, PL_stack_sp - PL_stack_base, *PL_markstack_ptr, mark);
  });
 
- PL_op = (OP *) &(MY_CXT.unwind_storage.return_op);
+ PL_op = (OP *) &(XSH_CXT.unwind_storage.return_op);
  PL_op = PL_op->op_ppaddr(aTHX);
 
  *PL_markstack_ptr = mark;
 
- MY_CXT.unwind_storage.proxy_op.op_next = PL_op;
- PL_op = &(MY_CXT.unwind_storage.proxy_op);
+ XSH_CXT.unwind_storage.proxy_op.op_next = PL_op;
+ PL_op = &(XSH_CXT.unwind_storage.proxy_op);
 }
 
-/* --- Uplevel ------------------------------------------------------------- */
-
-#ifndef OP_GIMME_REVERSE
-STATIC U8 su_op_gimme_reverse(U8 gimme) {
- switch (gimme) {
-  case G_VOID:
-   return OPf_WANT_VOID;
-  case G_ARRAY:
-   return OPf_WANT_LIST;
-  default:
-   break;
- }
+/* --- Yield --------------------------------------------------------------- */
 
- return OPf_WANT_SCALAR;
-}
-#define OP_GIMME_REVERSE(G) su_op_gimme_reverse(G)
+#if XSH_HAS_PERL(5, 10, 0)
+# define SU_RETOP_SUB(C)   ((C)->blk_sub.retop)
+# define SU_RETOP_EVAL(C)  ((C)->blk_eval.retop)
+# define SU_RETOP_LOOP(C)  ((C)->blk_loop.my_op->op_lastop->op_next)
+# define SU_RETOP_GIVEN(C) ((C)->blk_givwhen.leave_op->op_next)
+#else
+# define SU_RETOP_SUB(C)  ((C)->blk_oldretsp > 0 ? PL_retstack[(C)->blk_oldretsp - 1] : NULL)
+# define SU_RETOP_EVAL(C) SU_RETOP_SUB(C)
+# define SU_RETOP_LOOP(C) ((C)->blk_loop.last_op->op_next)
 #endif
 
-#define SU_UPLEVEL_SAVE(f, t) STMT_START { sud->old_##f = PL_##f; PL_##f = (t); } STMT_END
-#define SU_UPLEVEL_RESTORE(f) STMT_START { PL_##f = sud->old_##f; } STMT_END
-
-STATIC su_uplevel_ud *su_uplevel_storage_new(pTHX) {
-#define su_uplevel_storage_new() su_uplevel_storage_new(aTHX)
- su_uplevel_ud *sud;
- dMY_CXT;
-
- sud = MY_CXT.uplevel_storage.root;
- if (sud) {
-  MY_CXT.uplevel_storage.root = sud->next;
-  MY_CXT.uplevel_storage.count--;
- } else {
-  sud = su_uplevel_ud_new();
- }
-
- sud->next = MY_CXT.uplevel_storage.top;
- MY_CXT.uplevel_storage.top = sud;
-
- return sud;
-}
-
-STATIC void su_uplevel_storage_delete(pTHX_ su_uplevel_ud *sud) {
-#define su_uplevel_storage_delete(S) su_uplevel_storage_delete(aTHX_ (S))
- dMY_CXT;
-
- MY_CXT.uplevel_storage.top = sud->next;
+static void su_yield(pTHX_ void *ud_) {
+ dXSH_CXT;
+ PERL_CONTEXT *cx;
+ const char   *which = ud_;
+ I32 cxix      = XSH_CXT.yield_storage.cxix;
+ I32 items     = XSH_CXT.yield_storage.items;
+ opcode  type  = OP_NULL;
+ U8      flags = 0;
+ OP     *next;
 
- if (MY_CXT.uplevel_storage.count >= SU_UPLEVEL_STORAGE_SIZE) {
-  su_uplevel_ud_delete(sud);
- } else {
-  sud->next = MY_CXT.uplevel_storage.root;
-  MY_CXT.uplevel_storage.root = sud;
-  MY_CXT.uplevel_storage.count++;
- }
-}
+ PERL_UNUSED_VAR(ud_);
 
-STATIC int su_uplevel_goto_static(const OP *o) {
- for (; o; o = o->op_sibling) {
-  /* goto ops are unops with kids. */
-  if (!(o->op_flags & OPf_KIDS))
-   continue;
+ cx = cxstack + cxix;
+ switch (CxTYPE(cx)) {
+  case CXt_BLOCK: {
+   I32 i, cur = cxstack_ix, n = 1;
+   OP *o = NULL;
+   /* Is this actually a given/when block? This may occur only when yield was
+    * called with HERE (or nothing) as the context. */
+#if XSH_HAS_PERL(5, 10, 0)
+   if (cxix > 0) {
+    PERL_CONTEXT *prev = cx - 1;
+    U8       prev_type = CxTYPE(prev);
+    if ((prev_type == CXt_GIVEN || prev_type == CXt_WHEN)
+        && (prev->blk_oldcop == cx->blk_oldcop)) {
+     cxix--;
+     cx = prev;
+     if (prev_type == CXt_GIVEN)
+      goto cxt_given;
+     else
+      goto cxt_when;
+    }
+   }
+#endif
+   type  = OP_LEAVE;
+   next  = NULL;
+   /* Bare blocks (that appear as do { ... } blocks, map { ... } blocks or
+    * constant folded blcoks) don't need to save the op to return to anywhere
+    * since 'last' isn't supposed to work inside them. So we climb higher in
+    * the context stack until we reach a context that has a return op (i.e. a
+    * sub, an eval, a format or a real loop), recording how many blocks we
+    * crossed. Then we follow the op_next chain until we get to the leave op
+    * that closes the original block, which we are assured to reach since
+    * everything is static (the blocks we have crossed cannot be evals or
+    * subroutine calls). */
+   for (i = cxix + 1; i <= cur; ++i) {
+    PERL_CONTEXT *cx2 = cxstack + i;
+    switch (CxTYPE(cx2)) {
+     case CXt_BLOCK:
+      ++n;
+      break;
+     case CXt_SUB:
+     case CXt_FORMAT:
+      o = SU_RETOP_SUB(cx2);
+      break;
+     case CXt_EVAL:
+      o = SU_RETOP_EVAL(cx2);
+      break;
+#if XSH_HAS_PERL(5, 11, 0)
+# if XSH_HAS_PERL(5, 23, 8)
+     case CXt_LOOP_ARY:
+     case CXt_LOOP_LIST:
+# else
+     case CXt_LOOP_FOR:
+# endif
+     case CXt_LOOP_PLAIN:
+     case CXt_LOOP_LAZYSV:
+     case CXt_LOOP_LAZYIV:
+#else
+     case CXt_LOOP:
+#endif
+      o = SU_RETOP_LOOP(cx2);
+      break;
+    }
+    if (o)
+     break;
+   }
+   if (!o)
+    o = PL_op;
+   while (n && o) {
+    /* We may find other enter/leave blocks on our way to the matching leave.
+     * Make sure the depth is incremented/decremented appropriately. */
+    if (o->op_type == OP_ENTER) {
+     ++n;
+    } else if (o->op_type == OP_LEAVE) {
+     --n;
+     if (!n) {
+      next = o->op_next;
+      break;
+     }
+    }
+    o = o->op_next;
+   }
+   break;
+  }
+  case CXt_SUB:
+  case CXt_FORMAT:
+   type = OP_LEAVESUB;
+   next = SU_RETOP_SUB(cx);
+   break;
+  case CXt_EVAL:
+   type = CxTRYBLOCK(cx) ? OP_LEAVETRY : OP_LEAVEEVAL;
+   next = SU_RETOP_EVAL(cx);
+   break;
+#if XSH_HAS_PERL(5, 11, 0)
+# if XSH_HAS_PERL(5, 23, 8)
+  case CXt_LOOP_ARY:
+  case CXt_LOOP_LIST:
+# else
+  case CXt_LOOP_FOR:
+# endif
+  case CXt_LOOP_PLAIN:
+  case CXt_LOOP_LAZYSV:
+  case CXt_LOOP_LAZYIV:
+#else
+  case CXt_LOOP:
+#endif
+   type = OP_LEAVELOOP;
+   next = SU_RETOP_LOOP(cx);
+   break;
+#if XSH_HAS_PERL(5, 10, 0)
+  case CXt_GIVEN:
+cxt_given:
+   type = OP_LEAVEGIVEN;
+   next = SU_RETOP_GIVEN(cx);
+   break;
+  case CXt_WHEN:
+cxt_when:
+#if XSH_HAS_PERL(5, 15, 1)
+   type   = OP_LEAVEWHEN;
+#else
+   type   = OP_BREAK;
+   flags |= OPf_SPECIAL;
+#endif
+   next   = NULL;
+   break;
+#endif
+  case CXt_SUBST:
+   croak("%s() can't target a substitution context", which);
+   break;
+  default:
+   croak("%s() doesn't know how to leave a %s context",
+          which,                         SU_CXNAME(cxstack + cxix));
+   break;
+ }
+
+ PL_stack_sp = XSH_CXT.yield_storage.savesp;
+#if XSH_HAS_PERL(5, 19, 4)
+ {
+  I32 i;
+  SV **sp = PL_stack_sp;
+  for (i = -items + 1; i <= 0; ++i)
+   if (!SvTEMP(sp[i]))
+    sv_2mortal(SvREFCNT_inc(sp[i]));
+ }
+#endif
+
+ if (cxstack_ix > cxix)
+  dounwind(cxix);
+
+ /* Copy the arguments passed to yield() where the leave op expects to find
+  * them. */
+ if (items)
+  Move(PL_stack_sp - items + 1, PL_stack_base + cx->blk_oldsp + 1, items, SV *);
+ PL_stack_sp = PL_stack_base + cx->blk_oldsp + items;
+
+ flags |= OP_GIMME_REVERSE(cx->blk_gimme);
+
+ XSH_CXT.yield_storage.leave_op.op_type   = type;
+ XSH_CXT.yield_storage.leave_op.op_ppaddr = PL_ppaddr[type];
+ XSH_CXT.yield_storage.leave_op.op_flags  = flags;
+ XSH_CXT.yield_storage.leave_op.op_next   = next;
+
+ PL_op = (OP *) &(XSH_CXT.yield_storage.leave_op);
+ PL_op = PL_op->op_ppaddr(aTHX);
+
+ XSH_CXT.yield_storage.proxy_op.op_next = PL_op;
+ PL_op = &(XSH_CXT.yield_storage.proxy_op);
+}
+
+/* --- Uplevel ------------------------------------------------------------- */
+
+#define SU_UPLEVEL_SAVE(f, t) STMT_START { sud->old_##f = PL_##f; PL_##f = (t); } STMT_END
+#define SU_UPLEVEL_RESTORE(f) STMT_START { PL_##f = sud->old_##f; } STMT_END
+
+static su_uplevel_ud *su_uplevel_storage_new(pTHX_ I32 cxix) {
+#define su_uplevel_storage_new(I) su_uplevel_storage_new(aTHX_ (I))
+ su_uplevel_ud *sud;
+ UV depth;
+ dXSH_CXT;
+
+ sud = XSH_CXT.uplevel_storage.root;
+ if (sud) {
+  XSH_CXT.uplevel_storage.root = sud->next;
+  XSH_CXT.uplevel_storage.count--;
+ } else {
+  sud = su_uplevel_ud_new();
+ }
+
+ sud->next = XSH_CXT.uplevel_storage.top;
+ XSH_CXT.uplevel_storage.top = sud;
+
+ depth = su_uid_depth(cxix);
+ su_uid_storage_dup(&sud->tmp_uid_storage, &XSH_CXT.uid_storage, depth);
+ sud->old_uid_storage = XSH_CXT.uid_storage;
+ XSH_CXT.uid_storage  = sud->tmp_uid_storage;
+
+ return sud;
+}
+
+#if XSH_HAS_PERL(5, 13, 7)
+
+static void su_uplevel_storage_delete(pTHX_ su_uplevel_ud *sud) {
+#define su_uplevel_storage_delete(S) su_uplevel_storage_delete(aTHX_ (S))
+ dXSH_CXT;
+
+ sud->tmp_uid_storage = XSH_CXT.uid_storage;
+ XSH_CXT.uid_storage   = sud->old_uid_storage;
+ {
+  su_uid *map;
+  STRLEN  i, alloc;
+  map   = sud->tmp_uid_storage.map;
+  alloc = sud->tmp_uid_storage.alloc;
+  for (i = 0; i < alloc; ++i)
+   map[i].flags &= ~SU_UID_ACTIVE;
+ }
+ XSH_CXT.uplevel_storage.top = sud->next;
+
+ if (XSH_CXT.uplevel_storage.count >= SU_UPLEVEL_STORAGE_SIZE) {
+  su_uplevel_ud_delete(sud);
+ } else {
+  sud->next = XSH_CXT.uplevel_storage.root;
+  XSH_CXT.uplevel_storage.root = sud;
+  XSH_CXT.uplevel_storage.count++;
+ }
+}
+
+#endif
+
+static int su_uplevel_goto_static(const OP *o) {
+ for (; o; o = OpSIBLING(o)) {
+  /* goto ops are unops with kids. */
+  if (!(o->op_flags & OPf_KIDS))
+   continue;
 
   switch (o->op_type) {
    case OP_LEAVEEVAL:
@@ -1015,7 +1492,7 @@ STATIC int su_uplevel_goto_static(const OP *o) {
    case OP_GOTO:
     return 1;
    default:
-    if (su_uplevel_goto_static(cUNOPo->op_first))
+    if (su_uplevel_goto_static(((const UNOP *) o)->op_first))
      return 1;
     break;
   }
@@ -1026,7 +1503,7 @@ STATIC int su_uplevel_goto_static(const OP *o) {
 
 #if SU_UPLEVEL_HIJACKS_RUNOPS
 
-STATIC int su_uplevel_goto_runops(pTHX) {
+static int su_uplevel_goto_runops(pTHX) {
 #define su_uplevel_goto_runops() su_uplevel_goto_runops(aTHX)
  register OP *op;
  dVAR;
@@ -1043,7 +1520,7 @@ STATIC int su_uplevel_goto_runops(pTHX) {
     switch (CxTYPE(cx)) {
      case CXt_SUB:
       if (CxHASARGS(cx)) {
-       argarray = cx->blk_sub.argarray;
+       argarray = CX_ARGARRAY(cx);
        goto done;
       }
       break;
@@ -1057,9 +1534,9 @@ STATIC int su_uplevel_goto_runops(pTHX) {
 
 done:
    if (argarray) {
-    dMY_CXT;
+    dXSH_CXT;
 
-    if (MY_CXT.uplevel_storage.top->cxix == cxix) {
+    if (XSH_CXT.uplevel_storage.top->cxix == cxix) {
      AV  *args  = GvAV(PL_defgv);
      I32  items = AvFILLp(args);
 
@@ -1072,7 +1549,7 @@ done:
 
   PL_op = op = op->op_ppaddr(aTHX);
 
-#if !SU_HAS_PERL(5, 13, 0)
+#if !XSH_HAS_PERL(5, 13, 0)
   PERL_ASYNC_CHECK();
 #endif
  } while (op);
@@ -1084,9 +1561,9 @@ done:
 
 #endif /* SU_UPLEVEL_HIJACKS_RUNOPS */
 
-#define su_at_underscore(C) AvARRAY(AvARRAY(CvPADLIST(C))[CvDEPTH(C)])[0]
+#define su_at_underscore(C) PadARRAY(PadlistARRAY(CvPADLIST(C))[CvDEPTH(C)])[0]
 
-STATIC void su_uplevel_restore(pTHX_ void *sus_) {
+static void su_uplevel_restore(pTHX_ void *sus_) {
  su_uplevel_ud *sud = sus_;
  PERL_SI *cur = sud->old_curstackinfo;
  PERL_SI *si  = sud->si;
@@ -1118,8 +1595,8 @@ STATIC void su_uplevel_restore(pTHX_ void *sus_) {
    * reached without a goto() happening, and the old argarray member is
    * actually our fake argarray. Destroy it properly in that case. */
   if (cx->blk_sub.cv == sud->renamed) {
-   SvREFCNT_dec(cx->blk_sub.argarray);
-   cx->blk_sub.argarray = argarray;
+   SvREFCNT_dec(CX_ARGARRAY(cx));
+   CX_ARGARRAY_set(cx, argarray);
   }
 
   CvDEPTH(sud->callback)--;
@@ -1130,8 +1607,10 @@ STATIC void su_uplevel_restore(pTHX_ void *sus_) {
   * depth to be 0, or perl would complain about it being "still in use".
   * But we *know* that it cannot be so. */
  if (sud->renamed) {
-  CvDEPTH(sud->renamed)   = 0;
-  CvPADLIST(sud->renamed) = NULL;
+  if (!CvISXSUB(sud->renamed)) {
+   CvDEPTH(sud->renamed)   = 0;
+   CvPADLIST(sud->renamed) = NULL;
+  }
   SvREFCNT_dec(sud->renamed);
  }
 
@@ -1190,7 +1669,7 @@ found_it:
    CvDEPTH(target) = sud->target_depth - levels;
    PL_curstackinfo->si_cxix = i - 1;
 
-#if !SU_HAS_PERL(5, 13, 1)
+#if !XSH_HAS_PERL(5, 13, 1)
    /* Since $@ was maybe localized between the target frame and the uplevel
     * call, we forcefully flush the save stack to get rid of it and then
     * reset $@ to its proper value. Note that the the call to
@@ -1224,26 +1703,29 @@ found_it:
   * pointer to the current context frame across this call. This means that we
   * can't free the temporary context stack we used for the uplevel call right
   * now, or that pointer upwards would point to garbage. */
-#if SU_HAS_PERL(5, 13, 7)
+#if XSH_HAS_PERL(5, 13, 7)
  /* This issue has been fixed in perl with commit 8f89e5a9, which was made
   * public in perl 5.13.7. */
  su_uplevel_storage_delete(sud);
 #else
  /* Otherwise, we just enqueue it back in the global storage list. */
  {
-  dMY_CXT;
+  dXSH_CXT;
+
+  sud->tmp_uid_storage = XSH_CXT.uid_storage;
+  XSH_CXT.uid_storage  = sud->old_uid_storage;
 
-  MY_CXT.uplevel_storage.top  = sud->next;
-  sud->next = MY_CXT.uplevel_storage.root;
-  MY_CXT.uplevel_storage.root = sud;
-  MY_CXT.uplevel_storage.count++;
+  XSH_CXT.uplevel_storage.top  = sud->next;
+  sud->next = XSH_CXT.uplevel_storage.root;
+  XSH_CXT.uplevel_storage.root = sud;
+  XSH_CXT.uplevel_storage.count++;
  }
 #endif
 
  return;
 }
 
-STATIC CV *su_cv_clone(pTHX_ CV *proto, GV *gv) {
+static CV *su_cv_clone(pTHX_ CV *proto, GV *gv) {
 #define su_cv_clone(P, G) su_cv_clone(aTHX_ (P), (G))
  dVAR;
  CV *cv;
@@ -1262,11 +1744,14 @@ STATIC CV *su_cv_clone(pTHX_ CV *proto, GV *gv) {
 #endif
 
  CvGV_set(cv, gv);
+#if SU_RELEASE && XSH_HAS_PERL_EXACT(5, 21, 4)
+ CvNAMED_off(cv);
+#endif
  CvSTASH_set(cv, CvSTASH(proto));
  /* Commit 4c74a7df, publicized with perl 5.13.3, began to add backrefs to
   * stashes. CvSTASH_set() started to do it as well with commit c68d95645
   * (which was part of perl 5.13.7). */
-#if SU_HAS_PERL(5, 13, 3) && !SU_HAS_PERL(5, 13, 7)
+#if XSH_HAS_PERL(5, 13, 3) && !XSH_HAS_PERL(5, 13, 7)
  if (CvSTASH(proto))
   Perl_sv_add_backref(aTHX_ CvSTASH(proto), MUTABLE_SV(cv));
 #endif
@@ -1279,13 +1764,13 @@ STATIC CV *su_cv_clone(pTHX_ CV *proto, GV *gv) {
   CvROOT(cv)       = OpREFCNT_inc(CvROOT(proto));
   OP_REFCNT_UNLOCK;
   CvSTART(cv)      = CvSTART(proto);
+  CvPADLIST(cv)    = CvPADLIST(proto);
  }
  CvOUTSIDE(cv)     = CvOUTSIDE(proto);
 #ifdef CVf_WEAKOUTSIDE
  if (!(CvFLAGS(proto) & CVf_WEAKOUTSIDE))
 #endif
   SvREFCNT_inc_simple_void(CvOUTSIDE(cv));
- CvPADLIST(cv)     = CvPADLIST(proto);
 #ifdef CvOUTSIDE_SEQ
  CvOUTSIDE_SEQ(cv) = CvOUTSIDE_SEQ(proto);
 #endif
@@ -1301,7 +1786,7 @@ STATIC CV *su_cv_clone(pTHX_ CV *proto, GV *gv) {
  return cv;
 }
 
-STATIC I32 su_uplevel(pTHX_ CV *callback, I32 cxix, I32 args) {
+static I32 su_uplevel(pTHX_ CV *callback, I32 cxix, I32 args) {
 #define su_uplevel(C, I, A) su_uplevel(aTHX_ (C), (I), (A))
  su_uplevel_ud *sud;
  const PERL_CONTEXT *cx = cxstack + cxix;
@@ -1324,7 +1809,7 @@ STATIC I32 su_uplevel(pTHX_ CV *callback, I32 cxix, I32 args) {
  old_mark = AvFILLp(PL_curstack) = PL_stack_sp - PL_stack_base;
  SPAGAIN;
 
- sud = su_uplevel_storage_new();
+ sud = su_uplevel_storage_new(cxix);
 
  sud->cxix     = cxix;
  sud->died     = 1;
@@ -1415,6 +1900,7 @@ STATIC I32 su_uplevel(pTHX_ CV *callback, I32 cxix, I32 args) {
 
  if ((PL_op = PL_ppaddr[OP_ENTERSUB](aTHX))) {
   PERL_CONTEXT *sub_cx = cxstack + cxstack_ix;
+  AV *argarray = CX_ARGARRAY(cx);
 
   /* If pp_entersub() returns a non-null OP, it means that the callback is not
    * an XSUB. */
@@ -1422,7 +1908,7 @@ STATIC I32 su_uplevel(pTHX_ CV *callback, I32 cxix, I32 args) {
   sud->callback = MUTABLE_CV(SvREFCNT_inc(callback));
   CvDEPTH(callback)++;
 
-  if (CxHASARGS(cx) && cx->blk_sub.argarray) {
+  if (CxHASARGS(cx) && argarray) {
    /* The call to pp_entersub() has saved the current @_ (in XS terms,
     * GvAV(PL_defgv)) in the savearray member, and has created a new argarray
     * with what we put on the stack. But we want to fake up the same arguments
@@ -1431,12 +1917,12 @@ STATIC I32 su_uplevel(pTHX_ CV *callback, I32 cxix, I32 args) {
    AV *av = newAV();
    AvREAL_off(av);
    AvREIFY_on(av);
-   av_extend(av, AvMAX(cx->blk_sub.argarray));
-   AvFILLp(av) = AvFILLp(cx->blk_sub.argarray);
-   Copy(AvARRAY(cx->blk_sub.argarray), AvARRAY(av), AvFILLp(av) + 1, SV *);
-   sub_cx->blk_sub.argarray = av;
+   av_extend(av, AvMAX(argarray));
+   AvFILLp(av) = AvFILLp(argarray);
+   Copy(AvARRAY(argarray), AvARRAY(av), AvFILLp(av) + 1, SV *);
+   CX_ARGARRAY_set(sub_cx, av);
   } else {
-   SvREFCNT_inc_simple_void(sub_cx->blk_sub.argarray);
+   SvREFCNT_inc_simple_void(CX_ARGARRAY(sub_cx));
   }
 
   if (su_uplevel_goto_static(CvROOT(renamed))) {
@@ -1480,13 +1966,349 @@ STATIC I32 su_uplevel(pTHX_ CV *callback, I32 cxix, I32 args) {
  return ret;
 }
 
-/* --- Interpreter setup/teardown ------------------------------------------ */
+/* --- Unique context ID --------------------------------------------------- */
+
+static su_uid *su_uid_storage_fetch(pTHX_ UV depth) {
+#define su_uid_storage_fetch(D) su_uid_storage_fetch(aTHX_ (D))
+ su_uid *map;
+ STRLEN  alloc;
+ dXSH_CXT;
+
+ map   = XSH_CXT.uid_storage.map;
+ alloc = XSH_CXT.uid_storage.alloc;
+
+ if (depth >= alloc) {
+  STRLEN i;
+
+  Renew(map, depth + 1, su_uid);
+  for (i = alloc; i <= depth; ++i) {
+   map[i].seq   = 0;
+   map[i].flags = 0;
+  }
+
+  XSH_CXT.uid_storage.map   = map;
+  XSH_CXT.uid_storage.alloc = depth + 1;
+ }
+
+ if (depth >= XSH_CXT.uid_storage.used)
+  XSH_CXT.uid_storage.used = depth + 1;
+
+ return map + depth;
+}
+
+static int su_uid_storage_check(pTHX_ UV depth, UV seq) {
+#define su_uid_storage_check(D, S) su_uid_storage_check(aTHX_ (D), (S))
+ su_uid *uid;
+ dXSH_CXT;
+
+ if (depth >= XSH_CXT.uid_storage.used)
+  return 0;
+
+ uid = XSH_CXT.uid_storage.map + depth;
+
+ return (uid->seq == seq) && (uid->flags & SU_UID_ACTIVE);
+}
+
+static SV *su_uid_get(pTHX_ I32 cxix) {
+#define su_uid_get(I) su_uid_get(aTHX_ (I))
+ su_uid *uid;
+ SV     *uid_sv;
+ UV      depth;
+
+ depth = su_uid_depth(cxix);
+ uid   = su_uid_storage_fetch(depth);
+
+ if (!(uid->flags & SU_UID_ACTIVE)) {
+  su_ud_uid *ud;
+
+  uid->seq    = su_uid_seq_next(depth);
+  uid->flags |= SU_UID_ACTIVE;
+
+  Newx(ud, 1, su_ud_uid);
+  SU_UD_TYPE(ud) = SU_UD_TYPE_UID;
+  ud->idx        = depth;
+  su_init(ud, cxix, SU_SAVE_DESTRUCTOR_SIZE);
+ }
+
+ uid_sv = sv_newmortal();
+ sv_setpvf(uid_sv, "%"UVuf"-%"UVuf, depth, uid->seq);
+
+ return uid_sv;
+}
+
+#ifdef grok_number
+
+#define su_grok_number(S, L, VP) grok_number((S), (L), (VP))
+
+#else /* grok_number */
+
+#define IS_NUMBER_IN_UV 0x1
+
+static int su_grok_number(pTHX_ const char *s, STRLEN len, UV *valuep) {
+#define su_grok_number(S, L, VP) su_grok_number(aTHX_ (S), (L), (VP))
+ STRLEN i;
+ SV *tmpsv;
+
+ /* This crude check should be good enough for a fallback implementation.
+  * Better be too strict than too lax. */
+ for (i = 0; i < len; ++i) {
+  if (!isDIGIT(s[i]))
+   return 0;
+ }
+
+ tmpsv = sv_newmortal();
+ sv_setpvn(tmpsv, s, len);
+ *valuep = sv_2uv(tmpsv);
+
+ return IS_NUMBER_IN_UV;
+}
+
+#endif /* !grok_number */
+
+static int su_uid_validate(pTHX_ SV *uid) {
+#define su_uid_validate(U) su_uid_validate(aTHX_ (U))
+ const char *s;
+ STRLEN len, p = 0;
+ UV depth, seq;
+ int type;
+
+ s = SvPV_const(uid, len);
+
+ while (p < len && s[p] != '-')
+  ++p;
+ if (p >= len)
+  croak("UID contains only one part");
+
+ type = su_grok_number(s, p, &depth);
+ if (type != IS_NUMBER_IN_UV)
+  croak("First UID part is not an unsigned integer");
+
+ ++p; /* Skip '-'. As we used to have p < len, len - (p + 1) >= 0. */
+
+ type = su_grok_number(s + p, len - p, &seq);
+ if (type != IS_NUMBER_IN_UV)
+  croak("Second UID part is not an unsigned integer");
+
+ return su_uid_storage_check(depth, seq);
+}
+
+/* --- Context operations -------------------------------------------------- */
+
+/* Remove sequences of BLOCKs having DB for stash, followed by a SUB context
+ * for the debugger callback. */
+
+static I32 su_context_skip_db(pTHX_ I32 cxix) {
+#define su_context_skip_db(C) su_context_skip_db(aTHX_ (C))
+ I32 i;
+
+ if (!PL_DBsub)
+  return cxix;
+
+ for (i = cxix; i > 0; --i) {
+  PERL_CONTEXT *cx = cxstack + i;
+
+  switch (CxTYPE(cx)) {
+#if XSH_HAS_PERL(5, 17, 1)
+   case CXt_LOOP_PLAIN:
+#endif
+   case CXt_BLOCK:
+    if (cx->blk_oldcop && CopSTASH(cx->blk_oldcop) == GvSTASH(PL_DBgv))
+     continue;
+    break;
+   case CXt_SUB:
+    if (cx->blk_sub.cv == GvCV(PL_DBsub)) {
+     cxix = i - 1;
+     continue;
+    }
+    break;
+   default:
+    break;
+  }
+
+  break;
+ }
+
+ return cxix;
+}
+
+
+static I32 su_context_normalize_up(pTHX_ I32 cxix) {
+#define su_context_normalize_up(C) su_context_normalize_up(aTHX_ (C))
+ PERL_CONTEXT *cx;
+
+ if (cxix <= 0)
+  return 0;
+
+ cx = cxstack + cxix;
+ if (CxTYPE(cx) == CXt_BLOCK) {
+  PERL_CONTEXT *prev = cx - 1;
+
+  switch (CxTYPE(prev)) {
+#if XSH_HAS_PERL(5, 10, 0)
+   case CXt_GIVEN:
+   case CXt_WHEN:
+#endif
+#if XSH_HAS_PERL(5, 11, 0)
+   /* That's the only subcategory that can cause an extra BLOCK context */
+   case CXt_LOOP_PLAIN:
+#else
+   case CXt_LOOP:
+#endif
+    if (cx->blk_oldcop == prev->blk_oldcop)
+     return cxix - 1;
+    break;
+   case CXt_SUBST:
+    if (cx->blk_oldcop && OpSIBLING(cx->blk_oldcop)
+                       && OpSIBLING(cx->blk_oldcop)->op_type == OP_SUBST)
+     return cxix - 1;
+    break;
+  }
+ }
+
+ return cxix;
+}
+
+static I32 su_context_normalize_down(pTHX_ I32 cxix) {
+#define su_context_normalize_down(C) su_context_normalize_down(aTHX_ (C))
+ PERL_CONTEXT *next;
+
+ if (cxix >= cxstack_ix)
+  return cxstack_ix;
+
+ next = cxstack + cxix + 1;
+ if (CxTYPE(next) == CXt_BLOCK) {
+  PERL_CONTEXT *cx = next - 1;
+
+  switch (CxTYPE(cx)) {
+#if XSH_HAS_PERL(5, 10, 0)
+   case CXt_GIVEN:
+   case CXt_WHEN:
+#endif
+#if XSH_HAS_PERL(5, 11, 0)
+   /* That's the only subcategory that can cause an extra BLOCK context */
+   case CXt_LOOP_PLAIN:
+#else
+   case CXt_LOOP:
+#endif
+    if (cx->blk_oldcop == next->blk_oldcop)
+     return cxix + 1;
+    break;
+   case CXt_SUBST:
+    if (next->blk_oldcop && OpSIBLING(next->blk_oldcop)
+                         && OpSIBLING(next->blk_oldcop)->op_type == OP_SUBST)
+     return cxix + 1;
+    break;
+  }
+ }
+
+ return cxix;
+}
+
+#define su_context_here() su_context_normalize_up(su_context_skip_db(cxstack_ix))
+
+static I32 su_context_gimme(pTHX_ I32 cxix) {
+#define su_context_gimme(C) su_context_gimme(aTHX_ (C))
+ I32 i;
+
+ for (i = cxix; i >= 0; --i) {
+  PERL_CONTEXT *cx = cxstack + i;
+
+  switch (CxTYPE(cx)) {
+   /* gimme is always G_ARRAY for loop contexts. */
+#if XSH_HAS_PERL(5, 11, 0)
+# if XSH_HAS_PERL(5, 23, 8)
+   case CXt_LOOP_ARY:
+   case CXt_LOOP_LIST:
+# else
+   case CXt_LOOP_FOR:
+# endif
+   case CXt_LOOP_PLAIN:
+   case CXt_LOOP_LAZYSV:
+   case CXt_LOOP_LAZYIV:
+#else
+   case CXt_LOOP:
+#endif
+   case CXt_SUBST: {
+    const COP *cop = cx->blk_oldcop;
+    if (cop && OpSIBLING(cop)) {
+     switch (OpSIBLING(cop)->op_flags & OPf_WANT) {
+      case OPf_WANT_VOID:
+       return G_VOID;
+      case OPf_WANT_SCALAR:
+       return G_SCALAR;
+      case OPf_WANT_LIST:
+       return G_ARRAY;
+      default:
+       break;
+     }
+    }
+    break;
+   }
+   default:
+    return CxGIMME(cx);
+    break;
+  }
+ }
+
+ return G_VOID;
+}
+
+/* --- Module setup/teardown ----------------------------------------------- */
+
+static void xsh_user_global_setup(pTHX) {
+ HV *stash;
+
+ MUTEX_INIT(&su_uid_seq_counter_mutex);
+
+ XSH_LOCK(&su_uid_seq_counter_mutex);
+ su_uid_seq_counter.seqs = NULL;
+ su_uid_seq_counter.size = 0;
+ XSH_UNLOCK(&su_uid_seq_counter_mutex);
+
+ stash = gv_stashpv(XSH_PACKAGE, 1);
+ newCONSTSUB(stash, "TOP",           newSViv(0));
+ newCONSTSUB(stash, "SU_THREADSAFE", newSVuv(XSH_THREADSAFE));
 
-STATIC void su_teardown(pTHX_ void *param) {
+ return;
+}
+
+static void xsh_user_local_setup(pTHX_ xsh_user_cxt_t *cxt) {
+ cxt->stack_placeholder = NULL;
+
+ /* NewOp() calls calloc() which just zeroes the memory with memset(). */
+ Zero(&(cxt->unwind_storage.return_op), 1, LISTOP);
+ cxt->unwind_storage.return_op.op_type   = OP_RETURN;
+ cxt->unwind_storage.return_op.op_ppaddr = PL_ppaddr[OP_RETURN];
+
+ Zero(&(cxt->unwind_storage.proxy_op), 1, OP);
+ cxt->unwind_storage.proxy_op.op_type   = OP_STUB;
+ cxt->unwind_storage.proxy_op.op_ppaddr = NULL;
+
+ Zero(&(cxt->yield_storage.leave_op), 1, UNOP);
+ cxt->yield_storage.leave_op.op_type   = OP_STUB;
+ cxt->yield_storage.leave_op.op_ppaddr = NULL;
+
+ Zero(&(cxt->yield_storage.proxy_op), 1, OP);
+ cxt->yield_storage.proxy_op.op_type   = OP_STUB;
+ cxt->yield_storage.proxy_op.op_ppaddr = NULL;
+
+ cxt->uplevel_storage.top   = NULL;
+ cxt->uplevel_storage.root  = NULL;
+ cxt->uplevel_storage.count = 0;
+
+ cxt->uid_storage.map   = NULL;
+ cxt->uid_storage.used  = 0;
+ cxt->uid_storage.alloc = 0;
+
+ return;
+}
+
+static void xsh_user_local_teardown(pTHX_ xsh_user_cxt_t *cxt) {
  su_uplevel_ud *cur;
- dMY_CXT;
 
- cur = MY_CXT.uplevel_storage.root;
+ Safefree(cxt->uid_storage.map);
+
+ cur = cxt->uplevel_storage.root;
  if (cur) {
   su_uplevel_ud *prev;
   do {
@@ -1499,77 +2321,34 @@ STATIC void su_teardown(pTHX_ void *param) {
  return;
 }
 
-STATIC void su_setup(pTHX) {
-#define su_setup() su_setup(aTHX)
- MY_CXT_INIT;
-
- MY_CXT.stack_placeholder = NULL;
+static void xsh_user_global_teardown(pTHX) {
+ XSH_LOCK(&su_uid_seq_counter_mutex);
+ PerlMemShared_free(su_uid_seq_counter.seqs);
+ su_uid_seq_counter.size = 0;
+ XSH_UNLOCK(&su_uid_seq_counter_mutex);
 
- /* NewOp() calls calloc() which just zeroes the memory with memset(). */
- Zero(&(MY_CXT.unwind_storage.return_op), 1, LISTOP);
- MY_CXT.unwind_storage.return_op.op_type   = OP_RETURN;
- MY_CXT.unwind_storage.return_op.op_ppaddr = PL_ppaddr[OP_RETURN];
-
- Zero(&(MY_CXT.unwind_storage.proxy_op), 1, OP);
- MY_CXT.unwind_storage.proxy_op.op_type   = OP_STUB;
- MY_CXT.unwind_storage.proxy_op.op_ppaddr = NULL;
-
- MY_CXT.uplevel_storage.top   = NULL;
- MY_CXT.uplevel_storage.root  = NULL;
- MY_CXT.uplevel_storage.count = 0;
-
- call_atexit(su_teardown, NULL);
+ MUTEX_DESTROY(&su_uid_seq_counter_mutex);
 
  return;
 }
 
 /* --- XS ------------------------------------------------------------------ */
 
-#if SU_HAS_PERL(5, 8, 9)
-# define SU_SKIP_DB_MAX 2
-#else
-# define SU_SKIP_DB_MAX 3
-#endif
-
-/* Skip context sequences of 1 to SU_SKIP_DB_MAX (included) block contexts
- * followed by a DB sub */
-
-#define SU_SKIP_DB(C) \
- STMT_START {         \
-  I32 skipped = 0;    \
-  PERL_CONTEXT *base = cxstack;      \
-  PERL_CONTEXT *cx   = base + (C);   \
-  while (cx >= base && (C) > skipped && CxTYPE(cx) == CXt_BLOCK) \
-   --cx, ++skipped;                  \
-  if (cx >= base && (C) > skipped) { \
-   switch (CxTYPE(cx)) {  \
-    case CXt_SUB:         \
-     if (skipped <= SU_SKIP_DB_MAX && cx->blk_sub.cv == GvCV(PL_DBsub)) \
-      (C) -= skipped + 1; \
-      break;              \
-    default:              \
-     break;               \
-   }                      \
-  }                       \
- } STMT_END
-
-#define SU_GET_CONTEXT(A, B)   \
- STMT_START {                  \
-  if (items > A) {             \
-   SV *csv = ST(B);            \
-   if (!SvOK(csv))             \
-    goto default_cx;           \
-   cxix = SvIV(csv);           \
-   if (cxix < 0)               \
-    cxix = 0;                  \
-   else if (cxix > cxstack_ix) \
-    cxix = cxstack_ix;         \
-  } else {                     \
-default_cx:                    \
-   cxix = cxstack_ix;          \
-   if (PL_DBsub)               \
-    SU_SKIP_DB(cxix);          \
-  }                            \
+#define SU_GET_CONTEXT(A, B, D) \
+ STMT_START {                   \
+  if (items > A) {              \
+   SV *csv = ST(B);             \
+   if (!SvOK(csv))              \
+    goto default_cx;            \
+   cxix = SvIV(csv);            \
+   if (cxix < 0)                \
+    cxix = 0;                   \
+   else if (cxix > cxstack_ix)  \
+    goto default_cx;            \
+  } else {                      \
+default_cx:                     \
+   cxix = (D);                  \
+  }                             \
  } STMT_END
 
 #define SU_GET_LEVEL(A, B) \
@@ -1585,7 +2364,11 @@ default_cx:                    \
   }                        \
  } STMT_END
 
-XS(XS_Scope__Upper_unwind); /* prototype to pass -Wmissing-prototypes */
+#if XSH_HAS_PERL(5, 10, 0)
+# define SU_INFO_COUNT 11
+#else
+# define SU_INFO_COUNT 10
+#endif
 
 XS(XS_Scope__Upper_unwind) {
 #ifdef dVAR
@@ -1593,13 +2376,13 @@ XS(XS_Scope__Upper_unwind) {
 #else
  dXSARGS;
 #endif
- dMY_CXT;
+ dXSH_CXT;
  I32 cxix;
 
  PERL_UNUSED_VAR(cv); /* -W */
  PERL_UNUSED_VAR(ax); /* -Wall */
 
- SU_GET_CONTEXT(0, items - 1);
+ SU_GET_CONTEXT(0, items - 1, cxstack_ix);
  do {
   PERL_CONTEXT *cx = cxstack + cxix;
   switch (CxTYPE(cx)) {
@@ -1608,17 +2391,18 @@ XS(XS_Scope__Upper_unwind) {
      continue;
    case CXt_EVAL:
    case CXt_FORMAT:
-    MY_CXT.unwind_storage.cxix  = cxix;
-    MY_CXT.unwind_storage.items = items;
+    XSH_CXT.unwind_storage.cxix   = cxix;
+    XSH_CXT.unwind_storage.items  = items;
+    XSH_CXT.unwind_storage.savesp = PL_stack_sp;
+    if (items > 0) {
+     XSH_CXT.unwind_storage.items--;
+     XSH_CXT.unwind_storage.savesp--;
+    }
     /* pp_entersub will want to sanitize the stack after returning from there
-     * Screw that, we're insane */
-    if (GIMME_V == G_SCALAR) {
-     MY_CXT.unwind_storage.savesp = PL_stack_sp;
-     /* dXSARGS calls POPMARK, so we need to match PL_markstack_ptr[1] */
+     * Screw that, we're insane!
+     * dXSARGS calls POPMARK, so we need to match PL_markstack_ptr[1] */
+    if (GIMME_V == G_SCALAR)
      PL_stack_sp = PL_stack_base + PL_markstack_ptr[1] + 1;
-    } else {
-     MY_CXT.unwind_storage.savesp = NULL;
-    }
     SAVEDESTRUCTOR_X(su_unwind, NULL);
     return;
    default:
@@ -1628,47 +2412,88 @@ XS(XS_Scope__Upper_unwind) {
  croak("Can't return outside a subroutine");
 }
 
+static const char su_yield_name[] = "yield";
+
+XS(XS_Scope__Upper_yield) {
+#ifdef dVAR
+ dVAR; dXSARGS;
+#else
+ dXSARGS;
+#endif
+ dXSH_CXT;
+ I32 cxix;
+
+ PERL_UNUSED_VAR(cv); /* -W */
+ PERL_UNUSED_VAR(ax); /* -Wall */
+
+ SU_GET_CONTEXT(0, items - 1, su_context_here());
+ XSH_CXT.yield_storage.cxix   = cxix;
+ XSH_CXT.yield_storage.items  = items;
+ XSH_CXT.yield_storage.savesp = PL_stack_sp;
+ if (items > 0) {
+  XSH_CXT.yield_storage.items--;
+  XSH_CXT.yield_storage.savesp--;
+ }
+ /* See XS_Scope__Upper_unwind */
+ if (GIMME_V == G_SCALAR)
+  PL_stack_sp = PL_stack_base + PL_markstack_ptr[1] + 1;
+ SAVEDESTRUCTOR_X(su_yield, su_yield_name);
+ return;
+}
+
+static const char su_leave_name[] = "leave";
+
+XS(XS_Scope__Upper_leave) {
+#ifdef dVAR
+ dVAR; dXSARGS;
+#else
+ dXSARGS;
+#endif
+ dXSH_CXT;
+
+ PERL_UNUSED_VAR(cv); /* -W */
+ PERL_UNUSED_VAR(ax); /* -Wall */
+
+ XSH_CXT.yield_storage.cxix   = su_context_here();
+ XSH_CXT.yield_storage.items  = items;
+ XSH_CXT.yield_storage.savesp = PL_stack_sp;
+ /* See XS_Scope__Upper_unwind */
+ if (GIMME_V == G_SCALAR)
+  PL_stack_sp = PL_stack_base + PL_markstack_ptr[1] + 1;
+ SAVEDESTRUCTOR_X(su_yield, su_leave_name);
+ return;
+}
+
 MODULE = Scope::Upper            PACKAGE = Scope::Upper
 
 PROTOTYPES: ENABLE
 
 BOOT:
 {
- HV *stash;
-
- stash = gv_stashpv(__PACKAGE__, 1);
- newCONSTSUB(stash, "TOP",           newSViv(0));
- newCONSTSUB(stash, "SU_THREADSAFE", newSVuv(SU_THREADSAFE));
-
+ xsh_setup();
  newXSproto("Scope::Upper::unwind", XS_Scope__Upper_unwind, file, NULL);
-
- su_setup();
+ newXSproto("Scope::Upper::yield",  XS_Scope__Upper_yield,  file, NULL);
+ newXSproto("Scope::Upper::leave",  XS_Scope__Upper_leave,  file, NULL);
 }
 
-#if SU_THREADSAFE
+#if XSH_THREADSAFE
 
 void
 CLONE(...)
 PROTOTYPE: DISABLE
 PPCODE:
- {
-  MY_CXT_CLONE;
-  MY_CXT.uplevel_storage.top   = NULL;
-  MY_CXT.uplevel_storage.root  = NULL;
-  MY_CXT.uplevel_storage.count = 0;
- }
+ xsh_clone();
  XSRETURN(0);
 
-#endif /* SU_THREADSAFE */
+#endif /* XSH_THREADSAFE */
 
 void
 HERE()
 PROTOTYPE:
 PREINIT:
- I32 cxix = cxstack_ix;
+ I32 cxix;
 PPCODE:
- if (PL_DBsub)
-  SU_SKIP_DB(cxix);
+ cxix = su_context_here();
  EXTEND(SP, 1);
  mPUSHi(cxix);
  XSRETURN(1);
@@ -1679,11 +2504,14 @@ PROTOTYPE: ;$
 PREINIT:
  I32 cxix;
 PPCODE:
- SU_GET_CONTEXT(0, 0);
- if (--cxix < 0)
-  cxix = 0;
- if (PL_DBsub)
-  SU_SKIP_DB(cxix);
+ SU_GET_CONTEXT(0, 0, su_context_here());
+ if (cxix > 0) {
+  --cxix;
+  cxix = su_context_skip_db(cxix);
+  cxix = su_context_normalize_up(cxix);
+ } else {
+  warn(su_stack_smash);
+ }
  EXTEND(SP, 1);
  mPUSHi(cxix);
  XSRETURN(1);
@@ -1694,7 +2522,7 @@ PROTOTYPE: ;$
 PREINIT:
  I32 cxix;
 PPCODE:
- SU_GET_CONTEXT(0, 0);
+ SU_GET_CONTEXT(0, 0, cxstack_ix);
  EXTEND(SP, 1);
  for (; cxix >= 0; --cxix) {
   PERL_CONTEXT *cx = cxstack + cxix;
@@ -1708,6 +2536,7 @@ PPCODE:
     XSRETURN(1);
   }
  }
+ warn(su_no_such_target, "subroutine");
  XSRETURN_UNDEF;
 
 void
@@ -1716,7 +2545,7 @@ PROTOTYPE: ;$
 PREINIT:
  I32 cxix;
 PPCODE:
- SU_GET_CONTEXT(0, 0);
+ SU_GET_CONTEXT(0, 0, cxstack_ix);
  EXTEND(SP, 1);
  for (; cxix >= 0; --cxix) {
   PERL_CONTEXT *cx = cxstack + cxix;
@@ -1728,6 +2557,7 @@ PPCODE:
     XSRETURN(1);
   }
  }
+ warn(su_no_such_target, "eval");
  XSRETURN_UNDEF;
 
 void
@@ -1737,19 +2567,15 @@ PREINIT:
  I32 cxix, level;
 PPCODE:
  SU_GET_LEVEL(0, 0);
- cxix = cxstack_ix;
- if (PL_DBsub) {
-  SU_SKIP_DB(cxix);
-  while (cxix > 0) {
-   if (--level < 0)
-    break;
-   --cxix;
-   SU_SKIP_DB(cxix);
+ cxix = su_context_here();
+ while (--level >= 0) {
+  if (cxix <= 0) {
+   warn(su_stack_smash);
+   break;
   }
- } else {
-  cxix -= level;
-  if (cxix < 0)
-   cxix = 0;
+  --cxix;
+  cxix = su_context_skip_db(cxix);
+  cxix = su_context_normalize_up(cxix);
  }
  EXTEND(SP, 1);
  mPUSHi(cxix);
@@ -1776,6 +2602,8 @@ PPCODE:
   }
  }
 done:
+ if (level >= 0)
+  warn(su_stack_smash);
  EXTEND(SP, 1);
  mPUSHi(cxix);
  XSRETURN(1);
@@ -1786,12 +2614,14 @@ PROTOTYPE: ;$
 PREINIT:
  I32 cxix;
 PPCODE:
- SU_GET_CONTEXT(0, 0);
+ SU_GET_CONTEXT(0, 0, cxstack_ix);
  EXTEND(SP, 1);
  while (cxix > 0) {
   PERL_CONTEXT *cx = cxstack + cxix--;
   switch (CxTYPE(cx)) {
    case CXt_SUB:
+    if (PL_DBsub && cx->blk_sub.cv == GvCV(PL_DBsub))
+     continue;
    case CXt_EVAL:
    case CXt_FORMAT: {
     I32 gimme = cx->blk_gimme;
@@ -1806,6 +2636,162 @@ PPCODE:
  }
  XSRETURN_UNDEF;
 
+void
+context_info(...)
+PROTOTYPE: ;$
+PREINIT:
+ I32 cxix;
+ const PERL_CONTEXT *cx, *dbcx;
+ COP *cop;
+PPCODE:
+ SU_GET_CONTEXT(0, 0, su_context_skip_db(cxstack_ix));
+ cxix = su_context_normalize_up(cxix);
+ cx   = cxstack + cxix;
+ dbcx = cx;
+ if (PL_DBsub && cxix && (CxTYPE(cx) == CXt_SUB || CxTYPE(cx) == CXt_FORMAT)) {
+  I32 i = su_context_skip_db(cxix - 1) + 1;
+  if (i < cxix && CxTYPE(cxstack + i) == CXt_SUB)
+   cx = cxstack + i;
+ }
+ cop  = cx->blk_oldcop;
+ EXTEND(SP, SU_INFO_COUNT);
+ /* stash (0) */
+ {
+  HV *stash = CopSTASH(cop);
+  if (stash)
+   PUSHs(su_newmortal_pvn(HvNAME(stash), HvNAMELEN(stash)));
+  else
+   PUSHs(&PL_sv_undef);
+ }
+ /* file (1) */
+ PUSHs(su_newmortal_pvn(OutCopFILE(cop), OutCopFILE_len(cop)));
+ /* line (2) */
+ mPUSHi(CopLINE(cop));
+ /* subroutine (3) and has_args (4) */
+ switch (CxTYPE(cx)) {
+  case CXt_SUB:
+  case CXt_FORMAT: {
+   GV *cvgv = CvGV(dbcx->blk_sub.cv);
+   if (cvgv && isGV(cvgv)) {
+    SV *sv = sv_newmortal();
+    gv_efullname3(sv, cvgv, NULL);
+    PUSHs(sv);
+   } else {
+    PUSHs(su_newmortal_pvs("(unknown)"));
+   }
+   if (CxHASARGS(cx))
+    PUSHs(&PL_sv_yes);
+   else
+    PUSHs(&PL_sv_no);
+   break;
+  }
+  case CXt_EVAL:
+   PUSHs(su_newmortal_pvs("(eval)"));
+   mPUSHi(0);
+   break;
+  default:
+   PUSHs(&PL_sv_undef);
+   PUSHs(&PL_sv_undef);
+ }
+ /* gimme (5) */
+ switch (su_context_gimme(cxix)) {
+  case G_ARRAY:
+   PUSHs(&PL_sv_yes);
+   break;
+  case G_SCALAR:
+   PUSHs(&PL_sv_no);
+   break;
+  default: /* G_VOID */
+   PUSHs(&PL_sv_undef);
+   break;
+ }
+ /* eval text (6) and is_require (7) */
+ switch (CxTYPE(cx)) {
+  case CXt_EVAL:
+   if (CxOLD_OP_TYPE(cx) == OP_ENTEREVAL) {
+    /* eval STRING */
+#if XSH_HAS_PERL(5, 17, 4)
+    PUSHs(newSVpvn_flags(SvPVX(cx->blk_eval.cur_text),
+                         SvCUR(cx->blk_eval.cur_text)-2,
+                         SvUTF8(cx->blk_eval.cur_text)|SVs_TEMP));
+#else
+    PUSHs(cx->blk_eval.cur_text);
+#endif
+    PUSHs(&PL_sv_no);
+    break;
+   } else if (cx->blk_eval.old_namesv) {
+    /* require */
+    PUSHs(sv_mortalcopy(cx->blk_eval.old_namesv));
+    PUSHs(&PL_sv_yes);
+    break;
+   }
+   /* FALLTHROUGH */
+  default:
+   /* Anything else including eval BLOCK */
+   PUSHs(&PL_sv_undef);
+   PUSHs(&PL_sv_undef);
+   break;
+ }
+ /* hints (8) */
+ mPUSHi(CopHINTS_get(cop));
+ /* warnings (9) */
+ {
+  SV *mask = NULL;
+#if XSH_HAS_PERL(5, 9, 4)
+  STRLEN *old_warnings = cop->cop_warnings;
+#else
+  SV *old_warnings = cop->cop_warnings;
+#endif
+  if (old_warnings == pWARN_STD) {
+   if (PL_dowarn & G_WARN_ON)
+    goto context_info_warnings_on;
+   else
+#if XSH_HAS_PERL(5, 17, 4)
+    mask = &PL_sv_undef;
+#else
+    goto context_info_warnings_off;
+#endif
+  } else if (old_warnings == pWARN_NONE) {
+#if !XSH_HAS_PERL(5, 17, 4)
+context_info_warnings_off:
+#endif
+   mask = su_newmortal_pvn(WARN_NONEstring, WARNsize);
+  } else if (old_warnings == pWARN_ALL) {
+   HV *bits;
+context_info_warnings_on:
+#if XSH_HAS_PERL(5, 8, 7)
+   bits = get_hv("warnings::Bits", 0);
+   if (bits) {
+    SV **bits_all = hv_fetchs(bits, "all", FALSE);
+    if (bits_all)
+     mask = sv_mortalcopy(*bits_all);
+   }
+#endif
+   if (!mask)
+    mask = su_newmortal_pvn(WARN_ALLstring, WARNsize);
+  } else {
+#if XSH_HAS_PERL(5, 9, 4)
+   mask = su_newmortal_pvn((char *) (old_warnings + 1), old_warnings[0]);
+#else
+   mask = sv_mortalcopy(old_warnings);
+#endif
+  }
+  PUSHs(mask);
+ }
+#if XSH_HAS_PERL(5, 10, 0)
+ /* hints hash (10) */
+ {
+  COPHH *hints_hash = CopHINTHASH_get(cop);
+  if (hints_hash) {
+   SV *rhv = sv_2mortal(newRV_noinc((SV *) cophh_2hv(hints_hash, 0)));
+   PUSHs(rhv);
+  } else {
+   PUSHs(&PL_sv_undef);
+  }
+ }
+#endif
+ XSRETURN(SU_INFO_COUNT);
+
 void
 reap(SV *hook, ...)
 PROTOTYPE: &;$
@@ -1813,11 +2799,13 @@ PREINIT:
  I32 cxix;
  su_ud_reap *ud;
 CODE:
- SU_GET_CONTEXT(1, 1);
+ SU_GET_CONTEXT(1, 1, su_context_skip_db(cxstack_ix));
+ cxix = su_context_normalize_down(cxix);
  Newx(ud, 1, su_ud_reap);
- SU_UD_ORIGIN(ud)  = NULL;
- SU_UD_HANDLER(ud) = su_reap;
- ud->cb = newSVsv(hook);
+ SU_UD_TYPE(ud) = SU_UD_TYPE_REAP;
+ ud->cb         = (SvROK(hook) && SvTYPE(SvRV(hook)) >= SVt_PVCV)
+                  ? SvRV(hook) : hook;
+ SvREFCNT_inc_simple_void(ud->cb);
  su_init(ud, cxix, SU_SAVE_DESTRUCTOR_SIZE);
 
 void
@@ -1828,10 +2816,10 @@ PREINIT:
  I32 size;
  su_ud_localize *ud;
 CODE:
- SU_GET_CONTEXT(2, 2);
+ SU_GET_CONTEXT(2, 2, su_context_skip_db(cxstack_ix));
+ cxix = su_context_normalize_down(cxix);
  Newx(ud, 1, su_ud_localize);
- SU_UD_ORIGIN(ud)  = NULL;
- SU_UD_HANDLER(ud) = su_localize;
+ SU_UD_TYPE(ud) = SU_UD_TYPE_LOCALIZE;
  size = su_ud_localize_init(ud, sv, val, NULL);
  su_init(ud, cxix, size);
 
@@ -1845,12 +2833,14 @@ PREINIT:
 CODE:
  if (SvTYPE(sv) >= SVt_PVGV)
   croak("Can't infer the element localization type from a glob and the value");
- SU_GET_CONTEXT(3, 3);
+ SU_GET_CONTEXT(3, 3, su_context_skip_db(cxstack_ix));
+ cxix = su_context_normalize_down(cxix);
  Newx(ud, 1, su_ud_localize);
- SU_UD_ORIGIN(ud)  = NULL;
- SU_UD_HANDLER(ud) = su_localize;
+ /* Initialize SU_UD_ORIGIN(ud) in case SU_UD_LOCALIZE_FREE(ud) needs it */
+ SU_UD_ORIGIN(ud) = NULL;
+ SU_UD_TYPE(ud)   = SU_UD_TYPE_LOCALIZE;
  size = su_ud_localize_init(ud, sv, val, elem);
- if (ud->type != SVt_PVAV && ud->type != SVt_PVHV) {
+ if (SU_UD_PRIVATE(ud) != SVt_PVAV && SU_UD_PRIVATE(ud) != SVt_PVHV) {
   SU_UD_LOCALIZE_FREE(ud);
   croak("Can't localize an element of something that isn't an array or a hash");
  }
@@ -1864,10 +2854,10 @@ PREINIT:
  I32 size;
  su_ud_localize *ud;
 CODE:
- SU_GET_CONTEXT(2, 2);
+ SU_GET_CONTEXT(2, 2, su_context_skip_db(cxstack_ix));
+ cxix = su_context_normalize_down(cxix);
  Newx(ud, 1, su_ud_localize);
- SU_UD_ORIGIN(ud)  = NULL;
- SU_UD_HANDLER(ud) = su_localize;
+ SU_UD_TYPE(ud) = SU_UD_TYPE_LOCALIZE;
  size = su_ud_localize_init(ud, sv, NULL, elem);
  su_init(ud, cxix, size);
 
@@ -1881,7 +2871,7 @@ PPCODE:
   code = SvRV(code);
  if (SvTYPE(code) < SVt_PVCV)
   croak("First argument to uplevel must be a code reference");
- SU_GET_CONTEXT(1, items - 1);
+ SU_GET_CONTEXT(1, items - 1, cxstack_ix);
  do {
   PERL_CONTEXT *cx = cxstack + cxix;
   switch (CxTYPE(cx)) {
@@ -1904,3 +2894,27 @@ PPCODE:
   }
  } while (--cxix >= 0);
  croak("Can't uplevel outside a subroutine");
+
+void
+uid(...)
+PROTOTYPE: ;$
+PREINIT:
+ I32 cxix;
+ SV *uid;
+PPCODE:
+ SU_GET_CONTEXT(0, 0, su_context_here());
+ uid = su_uid_get(cxix);
+ EXTEND(SP, 1);
+ PUSHs(uid);
+ XSRETURN(1);
+
+void
+validate_uid(SV *uid)
+PROTOTYPE: $
+PREINIT:
+ SV *ret;
+PPCODE:
+ ret = su_uid_validate(uid) ? &PL_sv_yes : &PL_sv_no;
+ EXTEND(SP, 1);
+ PUSHs(ret);
+ XSRETURN(1);