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op.c: Remove assert exception for OP_REPEAT
[perl5.git] / regcomp.c
index 991d2f8..4556d1a 100644 (file)
--- a/regcomp.c
+++ b/regcomp.c
@@ -102,6 +102,25 @@ EXTERN_C const struct regexp_engine my_reg_engine;
 #define        STATIC  static
 #endif
 
+#ifndef MIN
+#define MIN(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
+/* this is a chain of data about sub patterns we are processing that
+   need to be handled separately/specially in study_chunk. Its so
+   we can simulate recursion without losing state.  */
+struct scan_frame;
+typedef struct scan_frame {
+    regnode *last_regnode;      /* last node to process in this frame */
+    regnode *next_regnode;      /* next node to process when last is reached */
+    U32 prev_recursed_depth;
+    I32 stopparen;              /* what stopparen do we use */
+    U32 is_top_frame;           /* what flags do we use? */
+
+    struct scan_frame *this_prev_frame; /* this previous frame */
+    struct scan_frame *prev_frame;      /* previous frame */
+    struct scan_frame *next_frame;      /* next frame */
+} scan_frame;
 
 struct RExC_state_t {
     U32                flags;                  /* RXf_* are we folding, multilining? */
@@ -149,7 +168,7 @@ struct RExC_state_t {
 
     regnode    **recurse;              /* Recurse regops */
     I32                recurse_count;          /* Number of recurse regops */
-    U8          *study_chunk_recursed;  /* bitmap of which parens we have moved
+    U8          *study_chunk_recursed;  /* bitmap of which subs we have moved
                                            through */
     U32         study_chunk_recursed_bytes;  /* bytes in bitmap */
     I32                in_lookbehind;
@@ -162,6 +181,9 @@ struct RExC_state_t {
     int                num_code_blocks;        /* size of code_blocks[] */
     int                code_index;             /* next code_blocks[] slot */
     SSize_t     maxlen;                        /* mininum possible number of chars in string to match */
+    scan_frame *frame_head;
+    scan_frame *frame_last;
+    U32         frame_count;
 #ifdef ADD_TO_REGEXEC
     char       *starttry;              /* -Dr: where regtry was called. */
 #define RExC_starttry  (pRExC_state->starttry)
@@ -171,9 +193,17 @@ struct RExC_state_t {
     const char  *lastparse;
     I32         lastnum;
     AV          *paren_name_list;       /* idx -> name */
+    U32         study_chunk_recursed_count;
+    SV          *mysv1;
+    SV          *mysv2;
 #define RExC_lastparse (pRExC_state->lastparse)
 #define RExC_lastnum   (pRExC_state->lastnum)
 #define RExC_paren_name_list    (pRExC_state->paren_name_list)
+#define RExC_study_chunk_recursed_count    (pRExC_state->study_chunk_recursed_count)
+#define RExC_mysv      (pRExC_state->mysv1)
+#define RExC_mysv1     (pRExC_state->mysv1)
+#define RExC_mysv2     (pRExC_state->mysv2)
+
 #endif
 };
 
@@ -195,7 +225,6 @@ struct RExC_state_t {
 #define RExC_emit_dummy        (pRExC_state->emit_dummy)
 #define RExC_emit_start        (pRExC_state->emit_start)
 #define RExC_emit_bound        (pRExC_state->emit_bound)
-#define RExC_naughty   (pRExC_state->naughty)
 #define RExC_sawback   (pRExC_state->sawback)
 #define RExC_seen      (pRExC_state->seen)
 #define RExC_size      (pRExC_state->size)
@@ -221,7 +250,23 @@ struct RExC_state_t {
 #define RExC_contains_i (pRExC_state->contains_i)
 #define RExC_override_recoding (pRExC_state->override_recoding)
 #define RExC_in_multi_char_class (pRExC_state->in_multi_char_class)
-
+#define RExC_frame_head (pRExC_state->frame_head)
+#define RExC_frame_last (pRExC_state->frame_last)
+#define RExC_frame_count (pRExC_state->frame_count)
+
+/* Heuristic check on the complexity of the pattern: if TOO_NAUGHTY, we set
+ * a flag to disable back-off on the fixed/floating substrings - if it's
+ * a high complexity pattern we assume the benefit of avoiding a full match
+ * is worth the cost of checking for the substrings even if they rarely help.
+ */
+#define RExC_naughty   (pRExC_state->naughty)
+#define TOO_NAUGHTY (10)
+#define MARK_NAUGHTY(add) \
+    if (RExC_naughty < TOO_NAUGHTY) \
+        RExC_naughty += (add)
+#define MARK_NAUGHTY_EXP(exp, add) \
+    if (RExC_naughty < TOO_NAUGHTY) \
+        RExC_naughty += RExC_naughty / (exp) + (add)
 
 #define        ISMULT1(c)      ((c) == '*' || (c) == '+' || (c) == '?')
 #define        ISMULT2(s)      ((*s) == '*' || (*s) == '+' || (*s) == '?' || \
@@ -377,24 +422,6 @@ typedef struct scan_data_t {
     regnode_ssc *start_class;
 } scan_data_t;
 
-/* The below is perhaps overboard, but this allows us to save a test at the
- * expense of a mask.  This is because on both EBCDIC and ASCII machines, 'A'
- * and 'a' differ by a single bit; the same with the upper and lower case of
- * all other ASCII-range alphabetics.  On ASCII platforms, they are 32 apart;
- * on EBCDIC, they are 64.  This uses an exclusive 'or' to find that bit and
- * then inverts it to form a mask, with just a single 0, in the bit position
- * where the upper- and lowercase differ.  XXX There are about 40 other
- * instances in the Perl core where this micro-optimization could be used.
- * Should decide if maintenance cost is worse, before changing those
- *
- * Returns a boolean as to whether or not 'v' is either a lowercase or
- * uppercase instance of 'c', where 'c' is in [A-Za-z].  If 'c' is a
- * compile-time constant, the generated code is better than some optimizing
- * compilers figure out, amounting to a mask and test.  The results are
- * meaningless if 'c' is not one of [A-Za-z] */
-#define isARG2_lower_or_UPPER_ARG1(c, v) \
-                              (((v) & ~('A' ^ 'a')) ==  ((c) & ~('A' ^ 'a')))
-
 /*
  * Forward declarations for pregcomp()'s friends.
  */
@@ -429,6 +456,10 @@ static const scan_data_t zero_scan_data =
 #define SCF_TRIE_RESTUDY        0x4000 /* Do restudy? */
 #define SCF_SEEN_ACCEPT         0x8000
 #define SCF_TRIE_DOING_RESTUDY 0x10000
+#define SCF_IN_DEFINE          0x20000
+
+
+
 
 #define UTF cBOOL(RExC_utf8)
 
@@ -513,7 +544,8 @@ static const scan_data_t zero_scan_data =
  * Simple_vFAIL -- like FAIL, but marks the current location in the scan
  */
 #define        Simple_vFAIL(m) STMT_START {                                    \
-    const IV offset = RExC_parse - RExC_precomp;                       \
+    const IV offset =                                                   \
+        (RExC_parse > RExC_end ? RExC_end : RExC_parse) - RExC_precomp; \
     Perl_croak(aTHX_ "%s" REPORT_LOCATION,                             \
            m, REPORT_LOCATION_ARGS(offset));   \
 } STMT_END
@@ -588,80 +620,85 @@ static const scan_data_t zero_scan_data =
             REPORT_LOCATION_ARGS(offset));         \
 } STMT_END
 
+/* These have asserts in them because of [perl #122671] Many warnings in
+ * regcomp.c can occur twice.  If they get output in pass1 and later in that
+ * pass, the pattern has to be converted to UTF-8 and the pass restarted, they
+ * would get output again.  So they should be output in pass2, and these
+ * asserts make sure new warnings follow that paradigm. */
 
 /* m is not necessarily a "literal string", in this macro */
 #define reg_warn_non_literal_string(loc, m) STMT_START {                \
     const IV offset = loc - RExC_precomp;                               \
-    Perl_warner(aTHX_ packWARN(WARN_REGEXP), "%s" REPORT_LOCATION,      \
+    __ASSERT_(PASS2) Perl_warner(aTHX_ packWARN(WARN_REGEXP), "%s" REPORT_LOCATION,      \
             m, REPORT_LOCATION_ARGS(offset));       \
 } STMT_END
 
 #define        ckWARNreg(loc,m) STMT_START {                                   \
     const IV offset = loc - RExC_precomp;                              \
-    Perl_ck_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,     \
+    __ASSERT_(PASS2) Perl_ck_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,    \
            REPORT_LOCATION_ARGS(offset));              \
 } STMT_END
 
 #define        vWARN_dep(loc, m) STMT_START {                                  \
     const IV offset = loc - RExC_precomp;                              \
-    Perl_warner(aTHX_ packWARN(WARN_DEPRECATED), m REPORT_LOCATION,    \
+    __ASSERT_(PASS2) Perl_warner(aTHX_ packWARN(WARN_DEPRECATED), m REPORT_LOCATION,   \
            REPORT_LOCATION_ARGS(offset));              \
 } STMT_END
 
 #define        ckWARNdep(loc,m) STMT_START {                                   \
     const IV offset = loc - RExC_precomp;                              \
-    Perl_ck_warner_d(aTHX_ packWARN(WARN_DEPRECATED),                  \
+    __ASSERT_(PASS2) Perl_ck_warner_d(aTHX_ packWARN(WARN_DEPRECATED),                 \
            m REPORT_LOCATION,                                          \
            REPORT_LOCATION_ARGS(offset));              \
 } STMT_END
 
 #define        ckWARNregdep(loc,m) STMT_START {                                \
     const IV offset = loc - RExC_precomp;                              \
-    Perl_ck_warner_d(aTHX_ packWARN2(WARN_DEPRECATED, WARN_REGEXP),    \
+    __ASSERT_(PASS2) Perl_ck_warner_d(aTHX_ packWARN2(WARN_DEPRECATED, WARN_REGEXP),   \
            m REPORT_LOCATION,                                          \
            REPORT_LOCATION_ARGS(offset));              \
 } STMT_END
 
 #define        ckWARN2reg_d(loc,m, a1) STMT_START {                            \
     const IV offset = loc - RExC_precomp;                              \
-    Perl_ck_warner_d(aTHX_ packWARN(WARN_REGEXP),                      \
+    __ASSERT_(PASS2) Perl_ck_warner_d(aTHX_ packWARN(WARN_REGEXP),                     \
            m REPORT_LOCATION,                                          \
            a1, REPORT_LOCATION_ARGS(offset));  \
 } STMT_END
 
 #define        ckWARN2reg(loc, m, a1) STMT_START {                             \
     const IV offset = loc - RExC_precomp;                              \
-    Perl_ck_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,     \
+    __ASSERT_(PASS2) Perl_ck_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,    \
            a1, REPORT_LOCATION_ARGS(offset));  \
 } STMT_END
 
 #define        vWARN3(loc, m, a1, a2) STMT_START {                             \
     const IV offset = loc - RExC_precomp;                              \
-    Perl_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,                \
+    __ASSERT_(PASS2) Perl_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,               \
            a1, a2, REPORT_LOCATION_ARGS(offset));      \
 } STMT_END
 
 #define        ckWARN3reg(loc, m, a1, a2) STMT_START {                         \
     const IV offset = loc - RExC_precomp;                              \
-    Perl_ck_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,     \
+    __ASSERT_(PASS2) Perl_ck_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,    \
            a1, a2, REPORT_LOCATION_ARGS(offset));      \
 } STMT_END
 
 #define        vWARN4(loc, m, a1, a2, a3) STMT_START {                         \
     const IV offset = loc - RExC_precomp;                              \
-    Perl_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,                \
+    __ASSERT_(PASS2) Perl_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,               \
            a1, a2, a3, REPORT_LOCATION_ARGS(offset)); \
 } STMT_END
 
 #define        ckWARN4reg(loc, m, a1, a2, a3) STMT_START {                     \
     const IV offset = loc - RExC_precomp;                              \
-    Perl_ck_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,     \
+    __ASSERT_(PASS2) Perl_ck_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,    \
            a1, a2, a3, REPORT_LOCATION_ARGS(offset)); \
 } STMT_END
 
 #define        vWARN5(loc, m, a1, a2, a3, a4) STMT_START {                     \
     const IV offset = loc - RExC_precomp;                              \
-    Perl_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,                \
+    __ASSERT_(PASS2) Perl_warner(aTHX_ packWARN(WARN_REGEXP), m REPORT_LOCATION,               \
            a1, a2, a3, a4, REPORT_LOCATION_ARGS(offset)); \
 } STMT_END
 
@@ -784,15 +821,44 @@ static const scan_data_t zero_scan_data =
             PerlIO_printf(Perl_debug_log,"\n");                             \
         });
 
+#define DEBUG_SHOW_STUDY_FLAG(flags,flag) \
+  if ((flags) & flag) PerlIO_printf(Perl_debug_log, "%s ", #flag)
+
+#define DEBUG_SHOW_STUDY_FLAGS(flags,open_str,close_str)                    \
+    if ( ( flags ) ) {                                                      \
+        PerlIO_printf(Perl_debug_log, "%s", open_str);                      \
+        DEBUG_SHOW_STUDY_FLAG(flags,SF_FL_BEFORE_SEOL);                     \
+        DEBUG_SHOW_STUDY_FLAG(flags,SF_FL_BEFORE_MEOL);                     \
+        DEBUG_SHOW_STUDY_FLAG(flags,SF_IS_INF);                             \
+        DEBUG_SHOW_STUDY_FLAG(flags,SF_HAS_PAR);                            \
+        DEBUG_SHOW_STUDY_FLAG(flags,SF_IN_PAR);                             \
+        DEBUG_SHOW_STUDY_FLAG(flags,SF_HAS_EVAL);                           \
+        DEBUG_SHOW_STUDY_FLAG(flags,SCF_DO_SUBSTR);                         \
+        DEBUG_SHOW_STUDY_FLAG(flags,SCF_DO_STCLASS_AND);                    \
+        DEBUG_SHOW_STUDY_FLAG(flags,SCF_DO_STCLASS_OR);                     \
+        DEBUG_SHOW_STUDY_FLAG(flags,SCF_DO_STCLASS);                        \
+        DEBUG_SHOW_STUDY_FLAG(flags,SCF_WHILEM_VISITED_POS);                \
+        DEBUG_SHOW_STUDY_FLAG(flags,SCF_TRIE_RESTUDY);                      \
+        DEBUG_SHOW_STUDY_FLAG(flags,SCF_SEEN_ACCEPT);                       \
+        DEBUG_SHOW_STUDY_FLAG(flags,SCF_TRIE_DOING_RESTUDY);                \
+        DEBUG_SHOW_STUDY_FLAG(flags,SCF_IN_DEFINE);                         \
+        PerlIO_printf(Perl_debug_log, "%s", close_str);                     \
+    }
+
+
 #define DEBUG_STUDYDATA(str,data,depth)                              \
 DEBUG_OPTIMISE_MORE_r(if(data){                                      \
     PerlIO_printf(Perl_debug_log,                                    \
         "%*s" str "Pos:%"IVdf"/%"IVdf                                \
-        " Flags: 0x%"UVXf" Whilem_c: %"IVdf" Lcp: %"IVdf" %s",       \
+        " Flags: 0x%"UVXf,                                           \
         (int)(depth)*2, "",                                          \
         (IV)((data)->pos_min),                                       \
         (IV)((data)->pos_delta),                                     \
-        (UV)((data)->flags),                                         \
+        (UV)((data)->flags)                                          \
+    );                                                               \
+    DEBUG_SHOW_STUDY_FLAGS((data)->flags," [ ","]");                 \
+    PerlIO_printf(Perl_debug_log,                                    \
+        " Whilem_c: %"IVdf" Lcp: %"IVdf" %s",                        \
         (IV)((data)->whilem_c),                                      \
         (IV)((data)->last_closep ? *((data)->last_closep) : -1),     \
         is_inf ? "INF " : ""                                         \
@@ -818,6 +884,33 @@ DEBUG_OPTIMISE_MORE_r(if(data){                                      \
     PerlIO_printf(Perl_debug_log,"\n");                              \
 });
 
+#ifdef DEBUGGING
+
+/* is c a control character for which we have a mnemonic? */
+#define isMNEMONIC_CNTRL(c) _IS_MNEMONIC_CNTRL_ONLY_FOR_USE_BY_REGCOMP_DOT_C(c)
+
+STATIC const char *
+S_cntrl_to_mnemonic(const U8 c)
+{
+    /* Returns the mnemonic string that represents character 'c', if one
+     * exists; NULL otherwise.  The only ones that exist for the purposes of
+     * this routine are a few control characters */
+
+    switch (c) {
+        case '\a':       return "\\a";
+        case '\b':       return "\\b";
+        case ESC_NATIVE: return "\\e";
+        case '\f':       return "\\f";
+        case '\n':       return "\\n";
+        case '\r':       return "\\r";
+        case '\t':       return "\\t";
+    }
+
+    return NULL;
+}
+
+#endif
+
 /* Mark that we cannot extend a found fixed substring at this point.
    Update the longest found anchored substring and the longest found
    floating substrings if needed. */
@@ -847,8 +940,8 @@ S_scan_commit(pTHX_ const RExC_state_t *pRExC_state, scan_data_t *data,
        else { /* *data->longest == data->longest_float */
            data->offset_float_min = l ? data->last_start_min : data->pos_min;
            data->offset_float_max = (l
-                                     ? data->last_start_max
-                                     : (data->pos_delta == SSize_t_MAX
+                          ? data->last_start_max
+                          : (data->pos_delta > SSize_t_MAX - data->pos_min
                                         ? SSize_t_MAX
                                         : data->pos_min + data->pos_delta));
            if (is_inf
@@ -891,7 +984,7 @@ S_ssc_anything(pTHX_ regnode_ssc *ssc)
 
     ssc->invlist = sv_2mortal(_new_invlist(2)); /* mortalize so won't leak */
     _append_range_to_invlist(ssc->invlist, 0, UV_MAX);
-    ANYOF_FLAGS(ssc) |= ANYOF_EMPTY_STRING;    /* Plus match empty string */
+    ANYOF_FLAGS(ssc) |= SSC_MATCHES_EMPTY_STRING;  /* Plus matches empty */
 }
 
 STATIC int
@@ -909,7 +1002,7 @@ S_ssc_is_anything(const regnode_ssc *ssc)
 
     assert(is_ANYOF_SYNTHETIC(ssc));
 
-    if (! (ANYOF_FLAGS(ssc) & ANYOF_EMPTY_STRING)) {
+    if (! (ANYOF_FLAGS(ssc) & SSC_MATCHES_EMPTY_STRING)) {
         return FALSE;
     }
 
@@ -948,7 +1041,7 @@ S_ssc_init(pTHX_ const RExC_state_t *pRExC_state, regnode_ssc *ssc)
 
     Zero(ssc, 1, regnode_ssc);
     set_ANYOF_SYNTHETIC(ssc);
-    ARG_SET(ssc, ANYOF_NONBITMAP_EMPTY);
+    ARG_SET(ssc, ANYOF_ONLY_HAS_BITMAP);
     ssc_anything(ssc);
 
     /* If any portion of the regex is to operate under locale rules,
@@ -1018,7 +1111,7 @@ S_get_ANYOF_cp_list_for_ssc(pTHX_ const RExC_state_t *pRExC_state,
     PERL_ARGS_ASSERT_GET_ANYOF_CP_LIST_FOR_SSC;
 
     /* Look at the data structure created by S_set_ANYOF_arg() */
-    if (n != ANYOF_NONBITMAP_EMPTY) {
+    if (n != ANYOF_ONLY_HAS_BITMAP) {
         SV * const rv = MUTABLE_SV(RExC_rxi->data->data[n]);
         AV * const av = MUTABLE_AV(SvRV(rv));
         SV **const ary = AvARRAY(av);
@@ -1048,15 +1141,16 @@ S_get_ANYOF_cp_list_for_ssc(pTHX_ const RExC_state_t *pRExC_state,
         }
     }
 
-    /* An ANYOF node contains a bitmap for the first 256 code points, and an
-     * inversion list for the others, but if there are code points that should
-     * match only conditionally on the target string being UTF-8, those are
-     * placed in the inversion list, and not the bitmap.  Since there are
-     * circumstances under which they could match, they are included in the
-     * SSC.  But if the ANYOF node is to be inverted, we have to exclude them
-     * here, so that when we invert below, the end result actually does include
-     * them.  (Think about "\xe0" =~ /[^\xc0]/di;).  We have to do this here
-     * before we add the unconditionally matched code points */
+    /* An ANYOF node contains a bitmap for the first NUM_ANYOF_CODE_POINTS
+     * code points, and an inversion list for the others, but if there are code
+     * points that should match only conditionally on the target string being
+     * UTF-8, those are placed in the inversion list, and not the bitmap.
+     * Since there are circumstances under which they could match, they are
+     * included in the SSC.  But if the ANYOF node is to be inverted, we have
+     * to exclude them here, so that when we invert below, the end result
+     * actually does include them.  (Think about "\xe0" =~ /[^\xc0]/di;).  We
+     * have to do this here before we add the unconditionally matched code
+     * points */
     if (ANYOF_FLAGS(node) & ANYOF_INVERT) {
         _invlist_intersection_complement_2nd(invlist,
                                              PL_UpperLatin1,
@@ -1064,7 +1158,7 @@ S_get_ANYOF_cp_list_for_ssc(pTHX_ const RExC_state_t *pRExC_state,
     }
 
     /* Add in the points from the bit map */
-    for (i = 0; i < 256; i++) {
+    for (i = 0; i < NUM_ANYOF_CODE_POINTS; i++) {
         if (ANYOF_BITMAP_TEST(node, i)) {
             invlist = add_cp_to_invlist(invlist, i);
             new_node_has_latin1 = TRUE;
@@ -1073,13 +1167,13 @@ S_get_ANYOF_cp_list_for_ssc(pTHX_ const RExC_state_t *pRExC_state,
 
     /* If this can match all upper Latin1 code points, have to add them
      * as well */
-    if (ANYOF_FLAGS(node) & ANYOF_NON_UTF8_NON_ASCII_ALL) {
+    if (ANYOF_FLAGS(node) & ANYOF_MATCHES_ALL_NON_UTF8_NON_ASCII) {
         _invlist_union(invlist, PL_UpperLatin1, &invlist);
     }
 
     /* Similarly for these */
-    if (ANYOF_FLAGS(node) & ANYOF_ABOVE_LATIN1_ALL) {
-        invlist = _add_range_to_invlist(invlist, 256, UV_MAX);
+    if (ANYOF_FLAGS(node) & ANYOF_MATCHES_ALL_ABOVE_BITMAP) {
+        _invlist_union_complement_2nd(invlist, PL_InBitmap, &invlist);
     }
 
     if (ANYOF_FLAGS(node) & ANYOF_INVERT) {
@@ -1112,8 +1206,8 @@ S_get_ANYOF_cp_list_for_ssc(pTHX_ const RExC_state_t *pRExC_state,
 #define ssc_match_all_cp(ssc) ssc_add_range(ssc, 0, UV_MAX)
 
 /* 'AND' a given class with another one.  Can create false positives.  'ssc'
- * should not be inverted.  'and_with->flags & ANYOF_POSIXL' should be 0 if
- * 'and_with' is a regnode_charclass instead of a regnode_ssc. */
+ * should not be inverted.  'and_with->flags & ANYOF_MATCHES_POSIXL' should be
+ * 0 if 'and_with' is a regnode_charclass instead of a regnode_ssc. */
 
 STATIC void
 S_ssc_and(pTHX_ const RExC_state_t *pRExC_state, regnode_ssc *ssc,
@@ -1204,7 +1298,7 @@ S_ssc_and(pTHX_ const RExC_state_t *pRExC_state, regnode_ssc *ssc,
 
         /* If either P1 or P2 is empty, the intersection will be also; can skip
          * the loop */
-        if (! (ANYOF_FLAGS(and_with) & ANYOF_POSIXL)) {
+        if (! (ANYOF_FLAGS(and_with) & ANYOF_MATCHES_POSIXL)) {
             ANYOF_POSIXL_ZERO(ssc);
         }
         else if (ANYOF_POSIXL_SSC_TEST_ANY_SET(ssc)) {
@@ -1263,16 +1357,16 @@ S_ssc_and(pTHX_ const RExC_state_t *pRExC_state, regnode_ssc *ssc,
             else {
                 ssc->invlist = anded_cp_list;
                 ANYOF_POSIXL_ZERO(ssc);
-                if (ANYOF_FLAGS(and_with) & ANYOF_POSIXL) {
+                if (ANYOF_FLAGS(and_with) & ANYOF_MATCHES_POSIXL) {
                     ANYOF_POSIXL_OR((regnode_charclass_posixl*) and_with, ssc);
                 }
             }
         }
         else if (ANYOF_POSIXL_SSC_TEST_ANY_SET(ssc)
-                 || (ANYOF_FLAGS(and_with) & ANYOF_POSIXL))
+                 || (ANYOF_FLAGS(and_with) & ANYOF_MATCHES_POSIXL))
         {
             /* One or the other of P1, P2 is non-empty. */
-            if (ANYOF_FLAGS(and_with) & ANYOF_POSIXL) {
+            if (ANYOF_FLAGS(and_with) & ANYOF_MATCHES_POSIXL) {
                 ANYOF_POSIXL_AND((regnode_charclass_posixl*) and_with, ssc);
             }
             ssc_union(ssc, anded_cp_list, FALSE);
@@ -1334,7 +1428,7 @@ S_ssc_or(pTHX_ const RExC_state_t *pRExC_state, regnode_ssc *ssc,
     {
         /* We ignore P2, leaving P1 going forward */
     }   /* else  Not inverted */
-    else if (ANYOF_FLAGS(or_with) & ANYOF_POSIXL) {
+    else if (ANYOF_FLAGS(or_with) & ANYOF_MATCHES_POSIXL) {
         ANYOF_POSIXL_OR((regnode_charclass_posixl*)or_with, ssc);
         if (ANYOF_POSIXL_SSC_TEST_ANY_SET(ssc)) {
             unsigned int i;
@@ -1423,12 +1517,78 @@ S_ssc_clear_locale(regnode_ssc *ssc)
     ANYOF_FLAGS(ssc) &= ~ANYOF_LOCALE_FLAGS;
 }
 
+#define NON_OTHER_COUNT   NON_OTHER_COUNT_FOR_USE_ONLY_BY_REGCOMP_DOT_C
+
+STATIC bool
+S_is_ssc_worth_it(const RExC_state_t * pRExC_state, const regnode_ssc * ssc)
+{
+    /* The synthetic start class is used to hopefully quickly winnow down
+     * places where a pattern could start a match in the target string.  If it
+     * doesn't really narrow things down that much, there isn't much point to
+     * having the overhead of using it.  This function uses some very crude
+     * heuristics to decide if to use the ssc or not.
+     *
+     * It returns TRUE if 'ssc' rules out more than half what it considers to
+     * be the "likely" possible matches, but of course it doesn't know what the
+     * actual things being matched are going to be; these are only guesses
+     *
+     * For /l matches, it assumes that the only likely matches are going to be
+     *      in the 0-255 range, uniformly distributed, so half of that is 127
+     * For /a and /d matches, it assumes that the likely matches will be just
+     *      the ASCII range, so half of that is 63
+     * For /u and there isn't anything matching above the Latin1 range, it
+     *      assumes that that is the only range likely to be matched, and uses
+     *      half that as the cut-off: 127.  If anything matches above Latin1,
+     *      it assumes that all of Unicode could match (uniformly), except for
+     *      non-Unicode code points and things in the General Category "Other"
+     *      (unassigned, private use, surrogates, controls and formats).  This
+     *      is a much large number. */
+
+    const U32 max_match = (LOC)
+                          ? 127
+                          : (! UNI_SEMANTICS)
+                            ? 63
+                            : (invlist_highest(ssc->invlist) < 256)
+                              ? 127
+                              : ((NON_OTHER_COUNT + 1) / 2) - 1;
+    U32 count = 0;      /* Running total of number of code points matched by
+                           'ssc' */
+    UV start, end;      /* Start and end points of current range in inversion
+                           list */
+
+    PERL_ARGS_ASSERT_IS_SSC_WORTH_IT;
+
+    invlist_iterinit(ssc->invlist);
+    while (invlist_iternext(ssc->invlist, &start, &end)) {
+
+        /* /u is the only thing that we expect to match above 255; so if not /u
+         * and even if there are matches above 255, ignore them.  This catches
+         * things like \d under /d which does match the digits above 255, but
+         * since the pattern is /d, it is not likely to be expecting them */
+        if (! UNI_SEMANTICS) {
+            if (start > 255) {
+                break;
+            }
+            end = MIN(end, 255);
+        }
+        count += end - start + 1;
+        if (count > max_match) {
+            invlist_iterfinish(ssc->invlist);
+            return FALSE;
+        }
+    }
+
+    return TRUE;
+}
+
+
 STATIC void
 S_ssc_finalize(pTHX_ RExC_state_t *pRExC_state, regnode_ssc *ssc)
 {
     /* The inversion list in the SSC is marked mortal; now we need a more
      * permanent copy, which is stored the same way that is done in a regular
-     * ANYOF node, with the first 256 code points in a bit map */
+     * ANYOF node, with the first NUM_ANYOF_CODE_POINTS code points in a bit
+     * map */
 
     SV* invlist = invlist_clone(ssc->invlist);
 
@@ -1437,8 +1597,8 @@ S_ssc_finalize(pTHX_ RExC_state_t *pRExC_state, regnode_ssc *ssc)
     assert(is_ANYOF_SYNTHETIC(ssc));
 
     /* The code in this file assumes that all but these flags aren't relevant
-     * to the SSC, except ANYOF_EMPTY_STRING, which should be cleared by the
-     * time we reach here */
+     * to the SSC, except SSC_MATCHES_EMPTY_STRING, which should be cleared
+     * by the time we reach here */
     assert(! (ANYOF_FLAGS(ssc) & ~ANYOF_COMMON_FLAGS));
 
     populate_ANYOF_from_invlist( (regnode *) ssc, &invlist);
@@ -1450,7 +1610,7 @@ S_ssc_finalize(pTHX_ RExC_state_t *pRExC_state, regnode_ssc *ssc)
     ssc->invlist = NULL;
 
     if (ANYOF_POSIXL_SSC_TEST_ANY_SET(ssc)) {
-        ANYOF_FLAGS(ssc) |= ANYOF_POSIXL;
+        ANYOF_FLAGS(ssc) |= ANYOF_MATCHES_POSIXL;
     }
 
     assert(! (ANYOF_FLAGS(ssc) & ANYOF_LOCALE_FLAGS) || RExC_contains_locale);
@@ -3114,15 +3274,15 @@ S_construct_ahocorasick_from_trie(pTHX_ RExC_state_t *pRExC_state, regnode *sour
 
 #define DEBUG_PEEP(str,scan,depth) \
     DEBUG_OPTIMISE_r({if (scan){ \
-       SV * const mysv=sv_newmortal(); \
        regnode *Next = regnext(scan); \
-       regprop(RExC_rx, mysv, scan, NULL); \
-       PerlIO_printf(Perl_debug_log, "%*s" str ">%3d: %s (%d)\n", \
-       (int)depth*2, "", REG_NODE_NUM(scan), SvPV_nolen_const(mysv),\
-       Next ? (REG_NODE_NUM(Next)) : 0 ); \
+       regprop(RExC_rx, RExC_mysv, scan, NULL, pRExC_state); \
+       PerlIO_printf(Perl_debug_log, "%*s" str ">%3d: %s (%d)", \
+           (int)depth*2, "", REG_NODE_NUM(scan), SvPV_nolen_const(RExC_mysv),\
+           Next ? (REG_NODE_NUM(Next)) : 0 ); \
+       DEBUG_SHOW_STUDY_FLAGS(flags," [ ","]");\
+       PerlIO_printf(Perl_debug_log, "\n"); \
    }});
 
-
 /* The below joins as many adjacent EXACTish nodes as possible into a single
  * one.  The regop may be changed if the node(s) contain certain sequences that
  * require special handling.  The joining is only done if:
@@ -3516,8 +3676,8 @@ S_join_exact(pTHX_ RExC_state_t *pRExC_state, regnode *scan,
                 }
 
                 if (len == 2
-                    && isARG2_lower_or_UPPER_ARG1('s', *s)
-                    && isARG2_lower_or_UPPER_ARG1('s', *(s+1)))
+                    && isALPHA_FOLD_EQ(*s, 's')
+                    && isALPHA_FOLD_EQ(*(s+1), 's'))
                 {
 
                     /* EXACTF nodes need to know that the minimum length
@@ -3563,17 +3723,17 @@ S_join_exact(pTHX_ RExC_state_t *pRExC_state, regnode *scan,
     Newx(and_withp,1, regnode_ssc); \
     SAVEFREEPV(and_withp)
 
-/* this is a chain of data about sub patterns we are processing that
-   need to be handled separately/specially in study_chunk. Its so
-   we can simulate recursion without losing state.  */
-struct scan_frame;
-typedef struct scan_frame {
-    regnode *last;  /* last node to process in this frame */
-    regnode *next;  /* next node to process when last is reached */
-    struct scan_frame *prev; /*previous frame*/
-    U32 prev_recursed_depth;
-    I32 stop; /* what stopparen do we use */
-} scan_frame;
+
+static void
+S_unwind_scan_frames(pTHX_ const void *p)
+{
+    scan_frame *f= (scan_frame *)p;
+    do {
+        scan_frame *n= f->next_frame;
+        Safefree(f);
+        f= n;
+    } while (f);
+}
 
 
 STATIC SSize_t
@@ -3610,9 +3770,7 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
 
     PERL_ARGS_ASSERT_STUDY_CHUNK;
 
-#ifdef DEBUGGING
-    StructCopy(&zero_scan_data, &data_fake, scan_data_t);
-#endif
+
     if ( depth == 0 ) {
         while (first_non_open && OP(first_non_open) == OPEN)
             first_non_open=regnext(first_non_open);
@@ -3620,35 +3778,50 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
 
 
   fake_study_recurse:
+    DEBUG_r(
+        RExC_study_chunk_recursed_count++;
+    );
+    DEBUG_OPTIMISE_MORE_r(
+    {
+        PerlIO_printf(Perl_debug_log,
+            "%*sstudy_chunk stopparen=%ld recursed_count=%lu depth=%lu recursed_depth=%lu scan=%p last=%p",
+            (int)(depth*2), "", (long)stopparen,
+            (unsigned long)RExC_study_chunk_recursed_count,
+            (unsigned long)depth, (unsigned long)recursed_depth,
+            scan,
+            last);
+        if (recursed_depth) {
+            U32 i;
+            U32 j;
+            for ( j = 0 ; j < recursed_depth ; j++ ) {
+                for ( i = 0 ; i < (U32)RExC_npar ; i++ ) {
+                    if (
+                        PAREN_TEST(RExC_study_chunk_recursed +
+                                   ( j * RExC_study_chunk_recursed_bytes), i )
+                        && (
+                            !j ||
+                            !PAREN_TEST(RExC_study_chunk_recursed +
+                                   (( j - 1 ) * RExC_study_chunk_recursed_bytes), i)
+                        )
+                    ) {
+                        PerlIO_printf(Perl_debug_log," %d",(int)i);
+                        break;
+                    }
+                }
+                if ( j + 1 < recursed_depth ) {
+                    PerlIO_printf(Perl_debug_log, ",");
+                }
+            }
+        }
+        PerlIO_printf(Perl_debug_log,"\n");
+    }
+    );
     while ( scan && OP(scan) != END && scan < last ){
         UV min_subtract = 0;    /* How mmany chars to subtract from the minimum
                                    node length to get a real minimum (because
                                    the folded version may be shorter) */
        bool unfolded_multi_char = FALSE;
        /* Peephole optimizer: */
-        DEBUG_OPTIMISE_MORE_r(
-        {
-            PerlIO_printf(Perl_debug_log,
-                "%*sstudy_chunk stopparen=%ld depth=%lu recursed_depth=%lu ",
-                ((int) depth*2), "", (long)stopparen,
-                (unsigned long)depth, (unsigned long)recursed_depth);
-            if (recursed_depth) {
-                U32 i;
-                U32 j;
-                for ( j = 0 ; j < recursed_depth ; j++ ) {
-                    PerlIO_printf(Perl_debug_log,"[");
-                    for ( i = 0 ; i < (U32)RExC_npar ; i++ )
-                        PerlIO_printf(Perl_debug_log,"%d",
-                            PAREN_TEST(RExC_study_chunk_recursed +
-                                       (j * RExC_study_chunk_recursed_bytes), i)
-                            ? 1 : 0
-                        );
-                    PerlIO_printf(Perl_debug_log,"]");
-                }
-            }
-            PerlIO_printf(Perl_debug_log,"\n");
-        }
-        );
         DEBUG_STUDYDATA("Peep:", data, depth);
         DEBUG_PEEP("Peep", scan, depth);
 
@@ -3682,17 +3855,47 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                NEXT_OFF(scan) = off;
        }
 
-
-
        /* The principal pseudo-switch.  Cannot be a switch, since we
           look into several different things.  */
-       if (OP(scan) == BRANCH || OP(scan) == BRANCHJ
-                  || OP(scan) == IFTHEN) {
+        if ( OP(scan) == DEFINEP ) {
+            SSize_t minlen = 0;
+            SSize_t deltanext = 0;
+            SSize_t fake_last_close = 0;
+            I32 f = SCF_IN_DEFINE;
+
+            StructCopy(&zero_scan_data, &data_fake, scan_data_t);
+            scan = regnext(scan);
+            assert( OP(scan) == IFTHEN );
+            DEBUG_PEEP("expect IFTHEN", scan, depth);
+
+            data_fake.last_closep= &fake_last_close;
+            minlen = *minlenp;
+            next = regnext(scan);
+            scan = NEXTOPER(NEXTOPER(scan));
+            DEBUG_PEEP("scan", scan, depth);
+            DEBUG_PEEP("next", next, depth);
+
+            /* we suppose the run is continuous, last=next...
+             * NOTE we dont use the return here! */
+            (void)study_chunk(pRExC_state, &scan, &minlen,
+                              &deltanext, next, &data_fake, stopparen,
+                              recursed_depth, NULL, f, depth+1);
+
+            scan = next;
+        } else
+        if (
+            OP(scan) == BRANCH  ||
+            OP(scan) == BRANCHJ ||
+            OP(scan) == IFTHEN
+        ) {
            next = regnext(scan);
            code = OP(scan);
-            /* demq: the op(next)==code check is to see if we have
-             * "branch-branch" AFAICT */
 
+            /* The op(next)==code check below is to see if we
+             * have "BRANCH-BRANCH", "BRANCHJ-BRANCHJ", "IFTHEN-IFTHEN"
+             * IFTHEN is special as it might not appear in pairs.
+             * Not sure whether BRANCH-BRANCHJ is possible, regardless
+             * we dont handle it cleanly. */
            if (OP(next) == code || code == IFTHEN) {
                 /* NOTE - There is similar code to this block below for
                  * handling TRIE nodes on a re-study.  If you change stuff here
@@ -3714,8 +3917,10 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                    I32 f = 0;
                    regnode_ssc this_class;
 
+                    DEBUG_PEEP("Branch", scan, depth);
+
                    num++;
-                   data_fake.flags = 0;
+                    StructCopy(&zero_scan_data, &data_fake, scan_data_t);
                    if (data) {
                        data_fake.whilem_c = data->whilem_c;
                        data_fake.last_closep = data->last_closep;
@@ -3725,9 +3930,11 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
 
                    data_fake.pos_delta = delta;
                    next = regnext(scan);
-                   scan = NEXTOPER(scan);
-                   if (code != BRANCH)
+
+                    scan = NEXTOPER(scan); /* everything */
+                    if (code != BRANCH)    /* everything but BRANCH */
                        scan = NEXTOPER(scan);
+
                    if (flags & SCF_DO_STCLASS) {
                        ssc_init(pRExC_state, &this_class);
                        data_fake.start_class = &this_class;
@@ -3740,6 +3947,7 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                    minnext = study_chunk(pRExC_state, &scan, minlenp,
                                       &deltanext, next, &data_fake, stopparen,
                                       recursed_depth, NULL, f,depth+1);
+
                    if (min1 > minnext)
                        min1 = minnext;
                    if (deltanext == SSize_t_MAX) {
@@ -3865,9 +4073,6 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                         U8 trietype = 0;
                         U32 count=0;
 
-#ifdef DEBUGGING
-                        SV * const mysv = sv_newmortal();   /* for dumping */
-#endif
                         /* var tail is used because there may be a TAIL
                            regop in the way. Ie, the exacts will point to the
                            thing following the TAIL, but the last branch will
@@ -3883,11 +4088,11 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
 
 
                         DEBUG_TRIE_COMPILE_r({
-                            regprop(RExC_rx, mysv, tail, NULL);
+                            regprop(RExC_rx, RExC_mysv, tail, NULL, pRExC_state);
                             PerlIO_printf( Perl_debug_log, "%*s%s%s\n",
                               (int)depth * 2 + 2, "",
                               "Looking for TRIE'able sequences. Tail node is: ",
-                              SvPV_nolen_const( mysv )
+                              SvPV_nolen_const( RExC_mysv )
                             );
                         });
 
@@ -3964,18 +4169,18 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
 #endif
 
                             DEBUG_TRIE_COMPILE_r({
-                                regprop(RExC_rx, mysv, cur, NULL);
+                                regprop(RExC_rx, RExC_mysv, cur, NULL, pRExC_state);
                                 PerlIO_printf( Perl_debug_log, "%*s- %s (%d)",
-                                   (int)depth * 2 + 2,"", SvPV_nolen_const( mysv ), REG_NODE_NUM(cur) );
+                                   (int)depth * 2 + 2,"", SvPV_nolen_const( RExC_mysv ), REG_NODE_NUM(cur) );
 
-                                regprop(RExC_rx, mysv, noper, NULL);
+                                regprop(RExC_rx, RExC_mysv, noper, NULL, pRExC_state);
                                 PerlIO_printf( Perl_debug_log, " -> %s",
-                                    SvPV_nolen_const(mysv));
+                                    SvPV_nolen_const(RExC_mysv));
 
                                 if ( noper_next ) {
-                                  regprop(RExC_rx, mysv, noper_next, NULL);
+                                  regprop(RExC_rx, RExC_mysv, noper_next, NULL, pRExC_state);
                                   PerlIO_printf( Perl_debug_log,"\t=> %s\t",
-                                    SvPV_nolen_const(mysv));
+                                    SvPV_nolen_const(RExC_mysv));
                                 }
                                 PerlIO_printf( Perl_debug_log, "(First==%d,Last==%d,Cur==%d,tt==%s,nt==%s,nnt==%s)\n",
                                    REG_NODE_NUM(first), REG_NODE_NUM(last), REG_NODE_NUM(cur),
@@ -4072,11 +4277,11 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                             } /* end handle unmergable node */
                         } /* loop over branches */
                         DEBUG_TRIE_COMPILE_r({
-                            regprop(RExC_rx, mysv, cur, NULL);
+                            regprop(RExC_rx, RExC_mysv, cur, NULL, pRExC_state);
                             PerlIO_printf( Perl_debug_log,
                               "%*s- %s (%d) <SCAN FINISHED>\n",
                               (int)depth * 2 + 2,
-                              "", SvPV_nolen_const( mysv ),REG_NODE_NUM(cur));
+                              "", SvPV_nolen_const( RExC_mysv ),REG_NODE_NUM(cur));
 
                         });
                         if ( last && trietype ) {
@@ -4112,10 +4317,10 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                                      * something like this: (?:|) So we can
                                      * turn it into a plain NOTHING op. */
                                     DEBUG_TRIE_COMPILE_r({
-                                        regprop(RExC_rx, mysv, cur, NULL);
+                                        regprop(RExC_rx, RExC_mysv, cur, NULL, pRExC_state);
                                         PerlIO_printf( Perl_debug_log,
                                           "%*s- %s (%d) <NOTHING BRANCH SEQUENCE>\n", (int)depth * 2 + 2,
-                                          "", SvPV_nolen_const( mysv ),REG_NODE_NUM(cur));
+                                          "", SvPV_nolen_const( RExC_mysv ),REG_NODE_NUM(cur));
 
                                     });
                                     OP(startbranch)= NOTHING;
@@ -4136,28 +4341,68 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                scan = NEXTOPER(scan);
            continue;
        } else if (OP(scan) == SUSPEND || OP(scan) == GOSUB || OP(scan) == GOSTART) {
-           scan_frame *newframe = NULL;
-           I32 paren;
-           regnode *start;
-           regnode *end;
+            I32 paren = 0;
+            regnode *start = NULL;
+            regnode *end = NULL;
             U32 my_recursed_depth= recursed_depth;
 
-           if (OP(scan) != SUSPEND) {
-                /* set the pointer */
+
+            if (OP(scan) != SUSPEND) { /* GOSUB/GOSTART */
+                /* Do setup, note this code has side effects beyond
+                 * the rest of this block. Specifically setting
+                 * RExC_recurse[] must happen at least once during
+                 * study_chunk(). */
                if (OP(scan) == GOSUB) {
                    paren = ARG(scan);
                    RExC_recurse[ARG2L(scan)] = scan;
                     start = RExC_open_parens[paren-1];
                     end   = RExC_close_parens[paren-1];
                 } else {
-                    paren = 0;
                     start = RExC_rxi->program + 1;
                     end   = RExC_opend;
                 }
-                if (!recursed_depth
+                /* NOTE we MUST always execute the above code, even
+                 * if we do nothing with a GOSUB/GOSTART */
+                if (
+                    ( flags & SCF_IN_DEFINE )
+                    ||
+                    (
+                        (is_inf_internal || is_inf || data->flags & SF_IS_INF)
+                        &&
+                        ( (flags & (SCF_DO_STCLASS | SCF_DO_SUBSTR)) == 0 )
+                    )
+                ) {
+                    /* no need to do anything here if we are in a define. */
+                    /* or we are after some kind of infinite construct
+                     * so we can skip recursing into this item.
+                     * Since it is infinite we will not change the maxlen
+                     * or delta, and if we miss something that might raise
+                     * the minlen it will merely pessimise a little.
+                     *
+                     * Iow /(?(DEFINE)(?<foo>foo|food))a+(?&foo)/
+                     * might result in a minlen of 1 and not of 4,
+                     * but this doesn't make us mismatch, just try a bit
+                     * harder than we should.
+                     * */
+                    scan= regnext(scan);
+                    continue;
+                }
+
+                if (
+                    !recursed_depth
                     ||
                     !PAREN_TEST(RExC_study_chunk_recursed + ((recursed_depth-1) * RExC_study_chunk_recursed_bytes), paren)
                 ) {
+                    /* it is quite possible that there are more efficient ways
+                     * to do this. We maintain a bitmap per level of recursion
+                     * of which patterns we have entered so we can detect if a
+                     * pattern creates a possible infinite loop. When we
+                     * recurse down a level we copy the previous levels bitmap
+                     * down. When we are at recursion level 0 we zero the top
+                     * level bitmap. It would be nice to implement a different
+                     * more efficient way of doing this. In particular the top
+                     * level bitmap may be unnecessary.
+                     */
                     if (!recursed_depth) {
                         Zero(RExC_study_chunk_recursed, RExC_study_chunk_recursed_bytes, U8);
                     } else {
@@ -4169,7 +4414,6 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                    DEBUG_STUDYDATA("set:", data,depth);
                     PAREN_SET(RExC_study_chunk_recursed + (recursed_depth * RExC_study_chunk_recursed_bytes), paren);
                     my_recursed_depth= recursed_depth + 1;
-                    Newx(newframe,1,scan_frame);
                 } else {
                    DEBUG_STUDYDATA("inf:", data,depth);
                     /* some form of infinite recursion, assume infinite length
@@ -4182,22 +4426,37 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                     if (flags & SCF_DO_STCLASS_OR) /* Allow everything */
                         ssc_anything(data->start_class);
                     flags &= ~SCF_DO_STCLASS;
+
+                    start= NULL; /* reset start so we dont recurse later on. */
                }
             } else {
-               Newx(newframe,1,scan_frame);
                paren = stopparen;
-               start = scan+2;
+                start = scan + 2;
                end = regnext(scan);
            }
-           if (newframe) {
-                assert(start);
+            if (start) {
+                scan_frame *newframe;
                 assert(end);
-               SAVEFREEPV(newframe);
-               newframe->next = regnext(scan);
-               newframe->last = last;
-               newframe->stop = stopparen;
-               newframe->prev = frame;
+                if (!RExC_frame_last) {
+                    Newxz(newframe, 1, scan_frame);
+                    SAVEDESTRUCTOR_X(S_unwind_scan_frames, newframe);
+                    RExC_frame_head= newframe;
+                    RExC_frame_count++;
+                } else if (!RExC_frame_last->next_frame) {
+                    Newxz(newframe,1,scan_frame);
+                    RExC_frame_last->next_frame= newframe;
+                    newframe->prev_frame= RExC_frame_last;
+                    RExC_frame_count++;
+                } else {
+                    newframe= RExC_frame_last->next_frame;
+                }
+                RExC_frame_last= newframe;
+
+                newframe->next_regnode = regnext(scan);
+                newframe->last_regnode = last;
+                newframe->stopparen = stopparen;
                 newframe->prev_recursed_depth = recursed_depth;
+                newframe->this_prev_frame= frame;
 
                 DEBUG_STUDYDATA("frame-new:",data,depth);
                 DEBUG_PEEP("fnew", scan, depth);
@@ -4251,7 +4510,7 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
              * can't match null string */
            if (flags & SCF_DO_STCLASS_AND) {
                 ssc_cp_and(data->start_class, uc);
-                ANYOF_FLAGS(data->start_class) &= ~ANYOF_EMPTY_STRING;
+                ANYOF_FLAGS(data->start_class) &= ~SSC_MATCHES_EMPTY_STRING;
                 ssc_clear_locale(data->start_class);
            }
            else if (flags & SCF_DO_STCLASS_OR) {
@@ -4259,16 +4518,13 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                ssc_and(pRExC_state, data->start_class, (regnode_charclass *) and_withp);
 
                 /* See commit msg 749e076fceedeb708a624933726e7989f2302f6a */
-                ANYOF_FLAGS(data->start_class) &= ~ANYOF_EMPTY_STRING;
+                ANYOF_FLAGS(data->start_class) &= ~SSC_MATCHES_EMPTY_STRING;
            }
            flags &= ~SCF_DO_STCLASS;
        }
-        else if (PL_regkind[OP(scan)] == EXACT) { /* But OP != EXACT!, so is
-                                                     EXACTFish */
+        else if (PL_regkind[OP(scan)] == EXACT) {
+            /* But OP != EXACT!, so is EXACTFish */
            SSize_t l = STR_LEN(scan);
-           UV uc = *((U8*)STRING(scan));
-            SV* EXACTF_invlist = _new_invlist(4); /* Start out big enough for 2
-                                                     separate code points */
             const U8 * s = (U8*)STRING(scan);
 
            /* Search for fixed substrings supports EXACT only. */
@@ -4277,7 +4533,6 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                 scan_commit(pRExC_state, data, minlenp, is_inf);
            }
            if (UTF) {
-               uc = utf8_to_uvchr_buf(s, s + l, NULL);
                l = utf8_length(s, s + l);
            }
            if (unfolded_multi_char) {
@@ -4297,156 +4552,27 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                }
            }
 
-            if (OP(scan) != EXACTFL && flags & SCF_DO_STCLASS_AND) {
-                ssc_clear_locale(data->start_class);
-            }
-
-            if (! UTF) {
-
-                /* We punt and assume can match anything if the node begins
-                 * with a multi-character fold.  Things are complicated.  For
-                 * example, /ffi/i could match any of:
-                 *  "\N{LATIN SMALL LIGATURE FFI}"
-                 *  "\N{LATIN SMALL LIGATURE FF}I"
-                 *  "F\N{LATIN SMALL LIGATURE FI}"
-                 *  plus several other things; and making sure we have all the
-                 *  possibilities is hard. */
-                if (is_MULTI_CHAR_FOLD_latin1_safe(s, s + STR_LEN(scan))) {
-                    EXACTF_invlist =
-                             _add_range_to_invlist(EXACTF_invlist, 0, UV_MAX);
-                }
-                else {
-
-                    /* Any Latin1 range character can potentially match any
-                     * other depending on the locale */
-                    if (OP(scan) == EXACTFL) {
-                        _invlist_union(EXACTF_invlist, PL_Latin1,
-                                                              &EXACTF_invlist);
-                    }
-                    else {
-                        /* But otherwise, it matches at least itself.  We can
-                         * quickly tell if it has a distinct fold, and if so,
-                         * it matches that as well */
-                        EXACTF_invlist = add_cp_to_invlist(EXACTF_invlist, uc);
-                        if (IS_IN_SOME_FOLD_L1(uc)) {
-                            EXACTF_invlist = add_cp_to_invlist(EXACTF_invlist,
-                                                           PL_fold_latin1[uc]);
-                        }
-                    }
-
-                    /* Some characters match above-Latin1 ones under /i.  This
-                     * is true of EXACTFL ones when the locale is UTF-8 */
-                    if (HAS_NONLATIN1_SIMPLE_FOLD_CLOSURE(uc)
-                        && (! isASCII(uc) || (OP(scan) != EXACTFA
-                                            && OP(scan) != EXACTFA_NO_TRIE)))
-                    {
-                        add_above_Latin1_folds(pRExC_state,
-                                               (U8) uc,
-                                               &EXACTF_invlist);
-                    }
-                }
-            }
-            else {  /* Pattern is UTF-8 */
-                U8 folded[UTF8_MAX_FOLD_CHAR_EXPAND * UTF8_MAXBYTES_CASE + 1] = { '\0' };
-                STRLEN foldlen = UTF8SKIP(s);
-                const U8* e = s + STR_LEN(scan);
-                SV** listp;
-
-                /* The only code points that aren't folded in a UTF EXACTFish
-                 * node are are the problematic ones in EXACTFL nodes */
-                if (OP(scan) == EXACTFL
-                    && is_PROBLEMATIC_LOCALE_FOLDEDS_START_cp(uc))
-                {
-                    /* We need to check for the possibility that this EXACTFL
-                     * node begins with a multi-char fold.  Therefore we fold
-                     * the first few characters of it so that we can make that
-                     * check */
-                    U8 *d = folded;
-                    int i;
-
-                    for (i = 0; i < UTF8_MAX_FOLD_CHAR_EXPAND && s < e; i++) {
-                        if (isASCII(*s)) {
-                            *(d++) = (U8) toFOLD(*s);
-                            s++;
-                        }
-                        else {
-                            STRLEN len;
-                            to_utf8_fold(s, d, &len);
-                            d += len;
-                            s += UTF8SKIP(s);
-                        }
-                    }
-
-                    /* And set up so the code below that looks in this folded
-                     * buffer instead of the node's string */
-                    e = d;
-                    foldlen = UTF8SKIP(folded);
-                    s = folded;
-                }
+            if (flags & SCF_DO_STCLASS) {
+                SV* EXACTF_invlist = _make_exactf_invlist(pRExC_state, scan);
 
-                /* When we reach here 's' points to the fold of the first
-                 * character(s) of the node; and 'e' points to far enough along
-                 * the folded string to be just past any possible multi-char
-                 * fold. 'foldlen' is the length in bytes of the first
-                 * character in 's'
-                 *
-                 * Unlike the non-UTF-8 case, the macro for determining if a
-                 * string is a multi-char fold requires all the characters to
-                 * already be folded.  This is because of all the complications
-                 * if not.  Note that they are folded anyway, except in EXACTFL
-                 * nodes.  Like the non-UTF case above, we punt if the node
-                 * begins with a multi-char fold  */
-
-                if (is_MULTI_CHAR_FOLD_utf8_safe(s, e)) {
-                    EXACTF_invlist =
-                             _add_range_to_invlist(EXACTF_invlist, 0, UV_MAX);
+                assert(EXACTF_invlist);
+                if (flags & SCF_DO_STCLASS_AND) {
+                    if (OP(scan) != EXACTFL)
+                        ssc_clear_locale(data->start_class);
+                    ANYOF_FLAGS(data->start_class) &= ~SSC_MATCHES_EMPTY_STRING;
+                    ANYOF_POSIXL_ZERO(data->start_class);
+                    ssc_intersection(data->start_class, EXACTF_invlist, FALSE);
                 }
-                else {  /* Single char fold */
-
-                    /* It matches all the things that fold to it, which are
-                     * found in PL_utf8_foldclosures (including itself) */
-                    EXACTF_invlist = add_cp_to_invlist(EXACTF_invlist, uc);
-                    if (! PL_utf8_foldclosures) {
-                        _load_PL_utf8_foldclosures();
-                    }
-                    if ((listp = hv_fetch(PL_utf8_foldclosures,
-                                        (char *) s, foldlen, FALSE)))
-                    {
-                        AV* list = (AV*) *listp;
-                        IV k;
-                        for (k = 0; k <= av_tindex(list); k++) {
-                            SV** c_p = av_fetch(list, k, FALSE);
-                            UV c;
-                            assert(c_p);
-
-                            c = SvUV(*c_p);
-
-                            /* /aa doesn't allow folds between ASCII and non- */
-                            if ((OP(scan) == EXACTFA || OP(scan) == EXACTFA_NO_TRIE)
-                                && isASCII(c) != isASCII(uc))
-                            {
-                                continue;
-                            }
+                else {  /* SCF_DO_STCLASS_OR */
+                    ssc_union(data->start_class, EXACTF_invlist, FALSE);
+                    ssc_and(pRExC_state, data->start_class, (regnode_charclass *) and_withp);
 
-                            EXACTF_invlist = add_cp_to_invlist(EXACTF_invlist, c);
-                        }
-                    }
+                    /* See commit msg 749e076fceedeb708a624933726e7989f2302f6a */
+                    ANYOF_FLAGS(data->start_class) &= ~SSC_MATCHES_EMPTY_STRING;
                 }
+                flags &= ~SCF_DO_STCLASS;
+                SvREFCNT_dec(EXACTF_invlist);
             }
-           if (flags & SCF_DO_STCLASS_AND) {
-                ANYOF_FLAGS(data->start_class) &= ~ANYOF_EMPTY_STRING;
-                ANYOF_POSIXL_ZERO(data->start_class);
-                ssc_intersection(data->start_class, EXACTF_invlist, FALSE);
-           }
-           else if (flags & SCF_DO_STCLASS_OR) {
-                ssc_union(data->start_class, EXACTF_invlist, FALSE);
-               ssc_and(pRExC_state, data->start_class, (regnode_charclass *) and_withp);
-
-                /* See commit msg 749e076fceedeb708a624933726e7989f2302f6a */
-                ANYOF_FLAGS(data->start_class) &= ~ANYOF_EMPTY_STRING;
-           }
-           flags &= ~SCF_DO_STCLASS;
-            SvREFCNT_dec(EXACTF_invlist);
        }
        else if (REGNODE_VARIES(OP(scan))) {
            SSize_t mincount, maxcount, minnext, deltanext, pos_before = 0;
@@ -4562,7 +4688,8 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                        flags &= ~SCF_DO_STCLASS_AND;
                        StructCopy(&this_class, data->start_class, regnode_ssc);
                        flags |= SCF_DO_STCLASS_OR;
-                        ANYOF_FLAGS(data->start_class) |= ANYOF_EMPTY_STRING;
+                        ANYOF_FLAGS(data->start_class)
+                                                |= SSC_MATCHES_EMPTY_STRING;
                    }
                } else {                /* Non-zero len */
                    if (flags & SCF_DO_STCLASS_OR) {
@@ -4585,8 +4712,11 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                {
                    /* Fatal warnings may leak the regexp without this: */
                    SAVEFREESV(RExC_rx_sv);
-                   ckWARNreg(RExC_parse,
-                           "Quantifier unexpected on zero-length expression");
+                   Perl_ck_warner(aTHX_ packWARN(WARN_REGEXP),
+                       "Quantifier unexpected on zero-length expression "
+                       "in regex m/%"UTF8f"/",
+                        UTF8fARG(UTF, RExC_end - RExC_precomp,
+                                 RExC_precomp));
                    (void)ReREFCNT_inc(RExC_rx_sv);
                }
 
@@ -4770,8 +4900,11 @@ S_study_chunk(pTHX_ RExC_state_t *pRExC_state, regnode **scanp,
                        } else {
                            /* start offset must point into the last copy */
                            data->last_start_min += minnext * (mincount - 1);
-                           data->last_start_max += is_inf ? SSize_t_MAX
-                               : (maxcount - 1) * (minnext + data->pos_delta);
+                           data->last_start_max =
+                              is_inf
+                               ? SSize_t_MAX
+                              : data->last_start_max +
+                                 (maxcount - 1) * (minnext + data->pos_delta);
                        }
                    }
                    /* It is counted once already... */
@@ -4858,7 +4991,8 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
                     ssc_intersection(data->start_class,
                                     PL_XPosix_ptrs[_CC_VERTSPACE], FALSE);
                     ssc_clear_locale(data->start_class);
-                    ANYOF_FLAGS(data->start_class) &= ~ANYOF_EMPTY_STRING;
+                    ANYOF_FLAGS(data->start_class)
+                                                &= ~SSC_MATCHES_EMPTY_STRING;
                 }
                 else if (flags & SCF_DO_STCLASS_OR) {
                     ssc_union(data->start_class,
@@ -4868,7 +5002,8 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
 
                     /* See commit msg for
                      * 749e076fceedeb708a624933726e7989f2302f6a */
-                    ANYOF_FLAGS(data->start_class) &= ~ANYOF_EMPTY_STRING;
+                    ANYOF_FLAGS(data->start_class)
+                                                &= ~SSC_MATCHES_EMPTY_STRING;
                 }
                flags &= ~SCF_DO_STCLASS;
             }
@@ -4891,11 +5026,11 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
            min++;
            if (flags & SCF_DO_STCLASS) {
                 bool invert = 0;
-                SV* my_invlist = sv_2mortal(_new_invlist(0));
+                SV* my_invlist = NULL;
                 U8 namedclass;
 
                 /* See commit msg 749e076fceedeb708a624933726e7989f2302f6a */
-                ANYOF_FLAGS(data->start_class) &= ~ANYOF_EMPTY_STRING;
+                ANYOF_FLAGS(data->start_class) &= ~SSC_MATCHES_EMPTY_STRING;
 
                /* Some of the logic below assumes that switching
                   locale on will only add false positives. */
@@ -4990,7 +5125,7 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
                     /* FALLTHROUGH */
                case POSIXA:
                     if (FLAGS(scan) == _CC_ASCII) {
-                        my_invlist = PL_XPosix_ptrs[_CC_ASCII];
+                        my_invlist = invlist_clone(PL_XPosix_ptrs[_CC_ASCII]);
                     }
                     else {
                         _invlist_intersection(PL_XPosix_ptrs[FLAGS(scan)],
@@ -5027,6 +5162,7 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
                         assert(flags & SCF_DO_STCLASS_OR);
                         ssc_union(data->start_class, my_invlist, invert);
                     }
+                    SvREFCNT_dec(my_invlist);
                }
                if (flags & SCF_DO_STCLASS_OR)
                    ssc_and(pRExC_state, data->start_class, (regnode_charclass *) and_withp);
@@ -5053,14 +5189,13 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
                 regnode *opt;
                 regnode *upto= regnext(scan);
                 DEBUG_PARSE_r({
-                    SV * const mysv_val=sv_newmortal();
                     DEBUG_STUDYDATA("OPFAIL",data,depth);
 
                     /*DEBUG_PARSE_MSG("opfail");*/
-                    regprop(RExC_rx, mysv_val, upto, NULL);
+                    regprop(RExC_rx, RExC_mysv, upto, NULL, pRExC_state);
                     PerlIO_printf(Perl_debug_log,
                         "~ replace with OPFAIL pointed at %s (%"IVdf") offset %"IVdf"\n",
-                        SvPV_nolen_const(mysv_val),
+                        SvPV_nolen_const(RExC_mysv),
                         (IV)REG_NODE_NUM(upto),
                         (IV)(upto - scan)
                     );
@@ -5084,7 +5219,7 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
                 regnode_ssc intrnl;
                 int f = 0;
 
-                data_fake.flags = 0;
+                StructCopy(&zero_scan_data, &data_fake, scan_data_t);
                 if (data) {
                     data_fake.whilem_c = data->whilem_c;
                     data_fake.last_closep = data->last_closep;
@@ -5136,7 +5271,8 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
                          * assertions are zero-length, so can match an EMPTY
                          * string */
                        ssc_and(pRExC_state, data->start_class, (regnode_charclass *) &intrnl);
-                        ANYOF_FLAGS(data->start_class) |= ANYOF_EMPTY_STRING;
+                        ANYOF_FLAGS(data->start_class)
+                                                   |= SSC_MATCHES_EMPTY_STRING;
                    }
                 }
            }
@@ -5208,7 +5344,7 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
 
                 if (f & SCF_DO_STCLASS_AND) {
                     ssc_and(pRExC_state, data->start_class, (regnode_charclass *) &intrnl);
-                    ANYOF_FLAGS(data->start_class) |= ANYOF_EMPTY_STRING;
+                    ANYOF_FLAGS(data->start_class) |= SSC_MATCHES_EMPTY_STRING;
                 }
                 if (data) {
                     if (data_fake.flags & (SF_HAS_PAR|SF_IN_PAR))
@@ -5327,7 +5463,7 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
                     SSize_t deltanext=0, minnext=0, f = 0, fake;
                     regnode_ssc this_class;
 
-                    data_fake.flags = 0;
+                    StructCopy(&zero_scan_data, &data_fake, scan_data_t);
                     if (data) {
                         data_fake.whilem_c = data->whilem_c;
                         data_fake.last_closep = data->last_closep;
@@ -5390,7 +5526,8 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
                     data->longest = &(data->longest_float);
             }
             min += min1;
-            delta += max1 - min1;
+            if (delta != SSize_t_MAX)
+                delta += max1 - min1;
             if (flags & SCF_DO_STCLASS_OR) {
                 ssc_or(pRExC_state, data->start_class, (regnode_charclass *) &accum);
                 if (min1) {
@@ -5450,16 +5587,19 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
     }
     */
     if (frame) {
+        depth = depth - 1;
+
         DEBUG_STUDYDATA("frame-end:",data,depth);
         DEBUG_PEEP("fend", scan, depth);
+
         /* restore previous context */
-        last = frame->last;
-        scan = frame->next;
-        stopparen = frame->stop;
+        last = frame->last_regnode;
+        scan = frame->next_regnode;
+        stopparen = frame->stopparen;
         recursed_depth = frame->prev_recursed_depth;
-        depth = depth - 1;
 
-        frame = frame->prev;
+        RExC_frame_last = frame->prev_frame;
+        frame = frame->this_prev_frame;
         goto fake_study_recurse;
     }
 
@@ -5497,7 +5637,7 @@ PerlIO_printf(Perl_debug_log, "LHS=%"UVuf" RHS=%"UVuf"\n",
         }
         return final_minlen;
     }
-    /* not-reached */
+    NOT_REACHED;
 }
 
 STATIC U32
@@ -5650,9 +5790,9 @@ S_pat_upgrade_to_utf8(pTHX_ RExC_state_t * const pRExC_state,
                    char **pat_p, STRLEN *plen_p, int num_code_blocks)
 {
     U8 *const src = (U8*)*pat_p;
-    U8 *dst;
+    U8 *dst, *d;
     int n=0;
-    STRLEN s = 0, d = 0;
+    STRLEN s = 0;
     bool do_end = 0;
     GET_RE_DEBUG_FLAGS_DECL;
 
@@ -5660,32 +5800,27 @@ S_pat_upgrade_to_utf8(pTHX_ RExC_state_t * const pRExC_state,
         "UTF8 mismatch! Converting to utf8 for resizing and compile\n"));
 
     Newx(dst, *plen_p * 2 + 1, U8);
+    d = dst;
 
     while (s < *plen_p) {
-        if (NATIVE_BYTE_IS_INVARIANT(src[s]))
-            dst[d]   = src[s];
-        else {
-            dst[d++] = UTF8_EIGHT_BIT_HI(src[s]);
-            dst[d]   = UTF8_EIGHT_BIT_LO(src[s]);
-        }
+        append_utf8_from_native_byte(src[s], &d);
         if (n < num_code_blocks) {
             if (!do_end && pRExC_state->code_blocks[n].start == s) {
-                pRExC_state->code_blocks[n].start = d;
-                assert(dst[d] == '(');
+                pRExC_state->code_blocks[n].start = d - dst - 1;
+                assert(*(d - 1) == '(');
                 do_end = 1;
             }
             else if (do_end && pRExC_state->code_blocks[n].end == s) {
-                pRExC_state->code_blocks[n].end = d;
-                assert(dst[d] == ')');
+                pRExC_state->code_blocks[n].end = d - dst - 1;
+                assert(*(d - 1) == ')');
                 do_end = 0;
                 n++;
             }
         }
         s++;
-        d++;
     }
-    dst[d] = '\0';
-    *plen_p = d;
+    *d = '\0';
+    *plen_p = d - dst;
     *pat_p = (char*) dst;
     SAVEFREEPV(*pat_p);
     RExC_orig_utf8 = RExC_utf8 = 1;
@@ -5755,7 +5890,7 @@ S_concat_pat(pTHX_ RExC_state_t * const pRExC_state,
             if (oplist) {
                 assert(oplist->op_type == OP_PADAV
                     || oplist->op_type == OP_RV2AV);
-                oplist = OP_SIBLING(oplist);
+                oplist = OpSIBLING(oplist);
             }
 
             if (SvRMAGICAL(av)) {
@@ -5802,10 +5937,10 @@ S_concat_pat(pTHX_ RExC_state_t * const pRExC_state,
                 pRExC_state->code_blocks[n].src_regex = NULL;
                 n++;
                 code = 1;
-                oplist = OP_SIBLING(oplist); /* skip CONST */
+                oplist = OpSIBLING(oplist); /* skip CONST */
                 assert(oplist);
             }
-            oplist = OP_SIBLING(oplist);;
+            oplist = OpSIBLING(oplist);;
         }
 
        /* apply magic and QR overloading to arg */
@@ -6039,7 +6174,6 @@ S_compile_runtime_code(pTHX_ RExC_state_t * const pRExC_state,
 
        ENTER;
        SAVETMPS;
-       save_re_context();
        PUSHSTACKi(PERLSI_REQUIRE);
         /* G_RE_REPARSING causes the toker to collapse \\ into \ when
          * parsing qr''; normally only q'' does this. It also alters
@@ -6288,6 +6422,13 @@ Perl_re_op_compile(pTHX_ SV ** const patternp, int pat_count,
         PL_utf8_foldable = _new_invlist_C_array(_Perl_Any_Folds_invlist);
         PL_HasMultiCharFold =
                        _new_invlist_C_array(_Perl_Folds_To_Multi_Char_invlist);
+
+        /* This is calculated here, because the Perl program that generates the
+         * static global ones doesn't currently have access to
+         * NUM_ANYOF_CODE_POINTS */
+       PL_InBitmap = _new_invlist(2);
+       PL_InBitmap = _add_range_to_invlist(PL_InBitmap, 0,
+                                                    NUM_ANYOF_CODE_POINTS - 1);
     }
 #endif
 
@@ -6303,7 +6444,7 @@ Perl_re_op_compile(pTHX_ SV ** const patternp, int pat_count,
        OP *o;
        int ncode = 0;
 
-       for (o = cLISTOPx(expr)->op_first; o; o = OP_SIBLING(o))
+       for (o = cLISTOPx(expr)->op_first; o; o = OpSIBLING(o))
            if (o->op_type == OP_NULL && (o->op_flags & OPf_SPECIAL))
                ncode++; /* count of DO blocks */
        if (ncode) {
@@ -6324,7 +6465,7 @@ Perl_re_op_compile(pTHX_ SV ** const patternp, int pat_count,
         if (expr->op_type == OP_CONST)
             n = 1;
         else
-            for (o = cLISTOPx(expr)->op_first; o; o = OP_SIBLING(o)) {
+            for (o = cLISTOPx(expr)->op_first; o; o = OpSIBLING(o)) {
                 if (o->op_type == OP_CONST)
                     n++;
             }
@@ -6340,7 +6481,7 @@ Perl_re_op_compile(pTHX_ SV ** const patternp, int pat_count,
         if (expr->op_type == OP_CONST)
             new_patternp[n] = cSVOPx_sv(expr);
         else
-            for (o = cLISTOPx(expr)->op_first; o; o = OP_SIBLING(o)) {
+            for (o = cLISTOPx(expr)->op_first; o; o = OpSIBLING(o)) {
                 if (o->op_type == OP_CONST)
                     new_patternp[n++] = cSVOPo_sv;
             }
@@ -6360,7 +6501,7 @@ Perl_re_op_compile(pTHX_ SV ** const patternp, int pat_count,
             assert(   expr->op_type == OP_PUSHMARK
                    || (expr->op_type == OP_NULL && expr->op_targ == OP_PUSHMARK)
                    || expr->op_type == OP_PADRANGE);
-            expr = OP_SIBLING(expr);
+            expr = OpSIBLING(expr);
     }
 
     pat = S_concat_pat(aTHX_ pRExC_state, NULL, new_patternp, pat_count,
@@ -6405,7 +6546,14 @@ Perl_re_op_compile(pTHX_ SV ** const patternp, int pat_count,
     RExC_contains_locale = 0;
     RExC_contains_i = 0;
     pRExC_state->runtime_code_qr = NULL;
+    RExC_frame_head= NULL;
+    RExC_frame_last= NULL;
+    RExC_frame_count= 0;
 
+    DEBUG_r({
+        RExC_mysv1= sv_newmortal();
+        RExC_mysv2= sv_newmortal();
+    });
     DEBUG_COMPILE_r({
             SV *dsv= sv_newmortal();
             RE_PV_QUOTED_DECL(s, RExC_utf8, dsv, exp, plen, 60);
@@ -6739,10 +6887,15 @@ Perl_re_op_compile(pTHX_ SV ** const patternp, int pat_count,
 
 reStudy:
     r->minlen = minlen = sawlookahead = sawplus = sawopen = sawminmod = 0;
+    DEBUG_r(
+        RExC_study_chunk_recursed_count= 0;
+    );
     Zero(r->substrs, 1, struct reg_substr_data);
-    if (RExC_study_chunk_recursed)
+    if (RExC_study_chunk_recursed) {
         Zero(RExC_study_chunk_recursed,
              RExC_study_chunk_recursed_bytes * RExC_npar, U8);
+    }
+
 
 #ifdef TRIE_STUDY_OPT
     if (!restudied) {
@@ -6770,7 +6923,7 @@ reStudy:
     if (UTF)
        SvUTF8_on(rx);  /* Unicode in it? */
     ri->regstclass = NULL;
-    if (RExC_naughty >= 10)    /* Probably an expensive pattern. */
+    if (RExC_naughty >= TOO_NAUGHTY)   /* Probably an expensive pattern. */
        r->intflags |= PREGf_NAUGHTY;
     scan = ri->program + 1;            /* First BRANCH. */
 
@@ -6850,9 +7003,7 @@ reStudy:
        else if (PL_regkind[OP(first)] == BOL) {
             r->intflags |= (OP(first) == MBOL
                            ? PREGf_ANCH_MBOL
-                          : (OP(first) == SBOL
-                              ? PREGf_ANCH_SBOL
-                              : PREGf_ANCH_BOL));
+                           : PREGf_ANCH_SBOL);
            first = NEXTOPER(first);
            goto again;
        }
@@ -7005,8 +7156,8 @@ reStudy:
 
        if ((!(r->anchored_substr || r->anchored_utf8) || r->anchored_offset)
            && stclass_flag
-            && ! (ANYOF_FLAGS(data.start_class) & ANYOF_EMPTY_STRING)
-           && !ssc_is_anything(data.start_class))
+            && ! (ANYOF_FLAGS(data.start_class) & SSC_MATCHES_EMPTY_STRING)
+           && is_ssc_worth_it(pRExC_state, data.start_class))
        {
            const U32 n = add_data(pRExC_state, STR_WITH_LEN("f"));
 
@@ -7019,7 +7170,7 @@ reStudy:
            ri->regstclass = (regnode*)RExC_rxi->data->data[n];
            r->intflags &= ~PREGf_SKIP; /* Used in find_byclass(). */
            DEBUG_COMPILE_r({ SV *sv = sv_newmortal();
-                     regprop(r, sv, (regnode*)data.start_class, NULL);
+                      regprop(r, sv, (regnode*)data.start_class, NULL, pRExC_state);
                      PerlIO_printf(Perl_debug_log,
                                    "synthetic stclass \"%s\".\n",
                                    SvPVX_const(sv));});
@@ -7085,8 +7236,8 @@ reStudy:
        r->check_substr = r->check_utf8 = r->anchored_substr = r->anchored_utf8
                = r->float_substr = r->float_utf8 = NULL;
 
-        if (! (ANYOF_FLAGS(data.start_class) & ANYOF_EMPTY_STRING)
-            && ! ssc_is_anything(data.start_class))
+        if (! (ANYOF_FLAGS(data.start_class) & SSC_MATCHES_EMPTY_STRING)
+           && is_ssc_worth_it(pRExC_state, data.start_class))
         {
            const U32 n = add_data(pRExC_state, STR_WITH_LEN("f"));
 
@@ -7099,7 +7250,7 @@ reStudy:
            ri->regstclass = (regnode*)RExC_rxi->data->data[n];
            r->intflags &= ~PREGf_SKIP; /* Used in find_byclass(). */
            DEBUG_COMPILE_r({ SV* sv = sv_newmortal();
-                     regprop(r, sv, (regnode*)data.start_class, NULL);
+                      regprop(r, sv, (regnode*)data.start_class, NULL, pRExC_state);
                      PerlIO_printf(Perl_debug_log,
                                    "synthetic stclass \"%s\".\n",
                                    SvPVX_const(sv));});
@@ -7118,8 +7269,8 @@ reStudy:
     /* Guard against an embedded (?=) or (?<=) with a longer minlen than
        the "real" pattern. */
     DEBUG_OPTIMISE_r({
-        PerlIO_printf(Perl_debug_log,"minlen: %"IVdf" r->minlen:%"IVdf" maxlen:%ld\n",
-                      (IV)minlen, (IV)r->minlen, RExC_maxlen);
+        PerlIO_printf(Perl_debug_log,"minlen: %"IVdf" r->minlen:%"IVdf" maxlen:%"IVdf"\n",
+                      (IV)minlen, (IV)r->minlen, (IV)RExC_maxlen);
     });
     r->minlenret = minlen;
     if (r->minlen < minlen)
@@ -7169,7 +7320,12 @@ reStudy:
 
         if (PL_regkind[fop] == NOTHING && nop == END)
             r->extflags |= RXf_NULL;
-        else if (PL_regkind[fop] == BOL && nop == END)
+        else if ((fop == MBOL || (fop == SBOL && !first->flags)) && nop == END)
+            /* when fop is SBOL first->flags will be true only when it was
+             * produced by parsing /\A/, and not when parsing /^/. This is
+             * very important for the split code as there we want to
+             * treat /^/ as /^/m, but we do not want to treat /\A/ as /^/m.
+             * See rt #122761 for more details. -- Yves */
             r->extflags |= RXf_START_ONLY;
         else if (fop == PLUS
                  && PL_regkind[nop] == POSIXD && FLAGS(next) == _CC_SPACE
@@ -7205,7 +7361,10 @@ reStudy:
     }
     Newxz(r->offs, RExC_npar, regexp_paren_pair);
     /* assume we don't need to swap parens around before we match */
-
+    DEBUG_TEST_r({
+        PerlIO_printf(Perl_debug_log,"study_chunk_recursed_count: %lu\n",
+            (unsigned long)RExC_study_chunk_recursed_count);
+    });
     DEBUG_DUMP_r({
         DEBUG_RExC_seen();
         PerlIO_printf(Perl_debug_log,"Final program:\n");
@@ -7737,28 +7896,26 @@ S_reg_scan_name(pTHX_ RExC_state_t *pRExC_state, U32 flags)
             Perl_croak(aTHX_ "panic: bad flag %lx in reg_scan_name",
                       (unsigned long) flags);
         }
-        assert(0); /* NOT REACHED */
+        NOT_REACHED; /* NOT REACHED */
     }
     return NULL;
 }
 
 #define DEBUG_PARSE_MSG(funcname)     DEBUG_PARSE_r({           \
-    int rem=(int)(RExC_end - RExC_parse);                       \
-    int cut;                                                    \
     int num;                                                    \
-    int iscut=0;                                                \
-    if (rem>10) {                                               \
-        rem=10;                                                 \
-        iscut=1;                                                \
-    }                                                           \
-    cut=10-rem;                                                 \
-    if (RExC_lastparse!=RExC_parse)                             \
-        PerlIO_printf(Perl_debug_log," >%.*s%-*s",              \
-            rem, RExC_parse,                                    \
-            cut + 4,                                            \
-            iscut ? "..." : "<"                                 \
+    if (RExC_lastparse!=RExC_parse) {                           \
+        PerlIO_printf(Perl_debug_log, "%s",                     \
+            Perl_pv_pretty(aTHX_ RExC_mysv1, RExC_parse,        \
+                RExC_end - RExC_parse, 16,                      \
+                "", "",                                         \
+                PERL_PV_ESCAPE_UNI_DETECT |                     \
+                PERL_PV_PRETTY_ELLIPSES   |                     \
+                PERL_PV_PRETTY_LTGT       |                     \
+                PERL_PV_ESCAPE_RE         |                     \
+                PERL_PV_PRETTY_EXACTSIZE                        \
+            )                                                   \
         );                                                      \
-    else                                                        \
+    } else                                                      \
         PerlIO_printf(Perl_debug_log,"%16s","");                \
                                                                 \
     if (SIZE_ONLY)                                              \
@@ -7896,6 +8053,8 @@ S_invlist_set_len(pTHX_ SV* const invlist, const UV len, const bool offset)
     assert(SvLEN(invlist) == 0 || SvCUR(invlist) <= SvLEN(invlist));
 }
 
+#ifndef PERL_IN_XSUB_RE
+
 PERL_STATIC_INLINE IV*
 S_get_invlist_previous_index_addr(SV* invlist)
 {
@@ -7930,6 +8089,28 @@ S_invlist_set_previous_index(SV* const invlist, const IV index)
     *get_invlist_previous_index_addr(invlist) = index;
 }
 
+PERL_STATIC_INLINE void
+S_invlist_trim(SV* const invlist)
+{
+    PERL_ARGS_ASSERT_INVLIST_TRIM;
+
+    assert(SvTYPE(invlist) == SVt_INVLIST);
+
+    /* Change the length of the inversion list to how many entries it currently
+     * has */
+    SvPV_shrink_to_cur((SV *) invlist);
+}
+
+PERL_STATIC_INLINE bool
+S_invlist_is_iterating(SV* const invlist)
+{
+    PERL_ARGS_ASSERT_INVLIST_IS_ITERATING;
+
+    return *(get_invlist_iter_addr(invlist)) < (STRLEN) UV_MAX;
+}
+
+#endif /* ifndef PERL_IN_XSUB_RE */
+
 PERL_STATIC_INLINE UV
 S_invlist_max(SV* const invlist)
 {
@@ -8049,18 +8230,6 @@ S_invlist_extend(pTHX_ SV* const invlist, const UV new_max)
     SvGROW((SV *)invlist, TO_INTERNAL_SIZE(new_max + 1));
 }
 
-PERL_STATIC_INLINE void
-S_invlist_trim(SV* const invlist)
-{
-    PERL_ARGS_ASSERT_INVLIST_TRIM;
-
-    assert(SvTYPE(invlist) == SVt_INVLIST);
-
-    /* Change the length of the inversion list to how many entries it currently
-     * has */
-    SvPV_shrink_to_cur((SV *) invlist);
-}
-
 STATIC void
 S__append_range_to_invlist(pTHX_ SV* const invlist,
                                  const UV start, const UV end)
@@ -8831,7 +9000,7 @@ Perl__add_range_to_invlist(pTHX_ SV* invlist, const UV start, const UV end)
     /* Add the range from 'start' to 'end' inclusive to the inversion list's
      * set.  A pointer to the inversion list is returned.  This may actually be
      * a new list, in which case the passed in one has been destroyed.  The
-     * passed in inversion list can be NULL, in which case a new one is created
+     * passed-in inversion list can be NULL, in which case a new one is created
      * with just the one range in it */
 
     SV* range_invlist;
@@ -9021,14 +9190,6 @@ S_invlist_iternext(SV* invlist, UV* start, UV* end)
     return TRUE;
 }
 
-PERL_STATIC_INLINE bool
-S_invlist_is_iterating(SV* const invlist)
-{
-    PERL_ARGS_ASSERT_INVLIST_IS_ITERATING;
-
-    return *(get_invlist_iter_addr(invlist)) < (STRLEN) UV_MAX;
-}
-
 PERL_STATIC_INLINE UV
 S_invlist_highest(SV* const invlist)
 {
@@ -9223,27 +9384,173 @@ S__invlistEQ(pTHX_ SV* const a, SV* const b, const bool complement_b)
 }
 #endif
 
-#undef HEADER_LENGTH
-#undef TO_INTERNAL_SIZE
-#undef FROM_INTERNAL_SIZE
-#undef INVLIST_VERSION_ID
-
-/* End of inversion list object */
-
-STATIC void
-S_parse_lparen_question_flags(pTHX_ RExC_state_t *pRExC_state)
+/*
+ * As best we can, determine the characters that can match the start of
+ * the given EXACTF-ish node.
+ *
+ * Returns the invlist as a new SV*; it is the caller's responsibility to
+ * call SvREFCNT_dec() when done with it.
+ */
+STATIC SV*
+S__make_exactf_invlist(pTHX_ RExC_state_t *pRExC_state, regnode *node)
 {
-    /* This parses the flags that are in either the '(?foo)' or '(?foo:bar)'
-     * constructs, and updates RExC_flags with them.  On input, RExC_parse
-     * should point to the first flag; it is updated on output to point to the
-     * final ')' or ':'.  There needs to be at least one flag, or this will
-     * abort */
+    const U8 * s = (U8*)STRING(node);
+    SSize_t bytelen = STR_LEN(node);
+    UV uc;
+    /* Start out big enough for 2 separate code points */
+    SV* invlist = _new_invlist(4);
+
+    PERL_ARGS_ASSERT__MAKE_EXACTF_INVLIST;
+
+    if (! UTF) {
+        uc = *s;
+
+        /* We punt and assume can match anything if the node begins
+         * with a multi-character fold.  Things are complicated.  For
+         * example, /ffi/i could match any of:
+         *  "\N{LATIN SMALL LIGATURE FFI}"
+         *  "\N{LATIN SMALL LIGATURE FF}I"
+         *  "F\N{LATIN SMALL LIGATURE FI}"
+         *  plus several other things; and making sure we have all the
+         *  possibilities is hard. */
+        if (is_MULTI_CHAR_FOLD_latin1_safe(s, s + bytelen)) {
+            invlist = _add_range_to_invlist(invlist, 0, UV_MAX);
+        }
+        else {
+            /* Any Latin1 range character can potentially match any
+             * other depending on the locale */
+            if (OP(node) == EXACTFL) {
+                _invlist_union(invlist, PL_Latin1, &invlist);
+            }
+            else {
+                /* But otherwise, it matches at least itself.  We can
+                 * quickly tell if it has a distinct fold, and if so,
+                 * it matches that as well */
+                invlist = add_cp_to_invlist(invlist, uc);
+                if (IS_IN_SOME_FOLD_L1(uc))
+                    invlist = add_cp_to_invlist(invlist, PL_fold_latin1[uc]);
+            }
 
-    /* for (?g), (?gc), and (?o) warnings; warning
-       about (?c) will warn about (?g) -- japhy    */
+            /* Some characters match above-Latin1 ones under /i.  This
+             * is true of EXACTFL ones when the locale is UTF-8 */
+            if (HAS_NONLATIN1_SIMPLE_FOLD_CLOSURE(uc)
+                && (! isASCII(uc) || (OP(node) != EXACTFA
+                                    && OP(node) != EXACTFA_NO_TRIE)))
+            {
+                add_above_Latin1_folds(pRExC_state, (U8) uc, &invlist);
+            }
+        }
+    }
+    else {  /* Pattern is UTF-8 */
+        U8 folded[UTF8_MAX_FOLD_CHAR_EXPAND * UTF8_MAXBYTES_CASE + 1] = { '\0' };
+        STRLEN foldlen = UTF8SKIP(s);
+        const U8* e = s + bytelen;
+        SV** listp;
+
+        uc = utf8_to_uvchr_buf(s, s + bytelen, NULL);
+
+        /* The only code points that aren't folded in a UTF EXACTFish
+         * node are are the problematic ones in EXACTFL nodes */
+        if (OP(node) == EXACTFL && is_PROBLEMATIC_LOCALE_FOLDEDS_START_cp(uc)) {
+            /* We need to check for the possibility that this EXACTFL
+             * node begins with a multi-char fold.  Therefore we fold
+             * the first few characters of it so that we can make that
+             * check */
+            U8 *d = folded;
+            int i;
 
-#define WASTED_O  0x01
-#define WASTED_G  0x02
+            for (i = 0; i < UTF8_MAX_FOLD_CHAR_EXPAND && s < e; i++) {
+                if (isASCII(*s)) {
+                    *(d++) = (U8) toFOLD(*s);
+                    s++;
+                }
+                else {
+                    STRLEN len;
+                    to_utf8_fold(s, d, &len);
+                    d += len;
+                    s += UTF8SKIP(s);
+                }
+            }
+
+            /* And set up so the code below that looks in this folded
+             * buffer instead of the node's string */
+            e = d;
+            foldlen = UTF8SKIP(folded);
+            s = folded;
+        }
+
+        /* When we reach here 's' points to the fold of the first
+         * character(s) of the node; and 'e' points to far enough along
+         * the folded string to be just past any possible multi-char
+         * fold. 'foldlen' is the length in bytes of the first
+         * character in 's'
+         *
+         * Unlike the non-UTF-8 case, the macro for determining if a
+         * string is a multi-char fold requires all the characters to
+         * already be folded.  This is because of all the complications
+         * if not.  Note that they are folded anyway, except in EXACTFL
+         * nodes.  Like the non-UTF case above, we punt if the node
+         * begins with a multi-char fold  */
+
+        if (is_MULTI_CHAR_FOLD_utf8_safe(s, e)) {
+            invlist = _add_range_to_invlist(invlist, 0, UV_MAX);
+        }
+        else {  /* Single char fold */
+
+            /* It matches all the things that fold to it, which are
+             * found in PL_utf8_foldclosures (including itself) */
+            invlist = add_cp_to_invlist(invlist, uc);
+            if (! PL_utf8_foldclosures)
+                _load_PL_utf8_foldclosures();
+            if ((listp = hv_fetch(PL_utf8_foldclosures,
+                                (char *) s, foldlen, FALSE)))
+            {
+                AV* list = (AV*) *listp;
+                IV k;
+                for (k = 0; k <= av_tindex(list); k++) {
+                    SV** c_p = av_fetch(list, k, FALSE);
+                    UV c;
+                    assert(c_p);
+
+                    c = SvUV(*c_p);
+
+                    /* /aa doesn't allow folds between ASCII and non- */
+                    if ((OP(node) == EXACTFA || OP(node) == EXACTFA_NO_TRIE)
+                        && isASCII(c) != isASCII(uc))
+                    {
+                        continue;
+                    }
+
+                    invlist = add_cp_to_invlist(invlist, c);
+                }
+            }
+        }
+    }
+
+    return invlist;
+}
+
+#undef HEADER_LENGTH
+#undef TO_INTERNAL_SIZE
+#undef FROM_INTERNAL_SIZE
+#undef INVLIST_VERSION_ID
+
+/* End of inversion list object */
+
+STATIC void
+S_parse_lparen_question_flags(pTHX_ RExC_state_t *pRExC_state)
+{
+    /* This parses the flags that are in either the '(?foo)' or '(?foo:bar)'
+     * constructs, and updates RExC_flags with them.  On input, RExC_parse
+     * should point to the first flag; it is updated on output to point to the
+     * final ')' or ':'.  There needs to be at least one flag, or this will
+     * abort */
+
+    /* for (?g), (?gc), and (?o) warnings; warning
+       about (?c) will warn about (?g) -- japhy    */
+
+#define WASTED_O  0x01
+#define WASTED_G  0x02
 #define WASTED_C  0x04
 #define WASTED_GC (WASTED_G|WASTED_C)
     I32 wastedflags = 0x00;
@@ -9253,6 +9560,7 @@ S_parse_lparen_question_flags(pTHX_ RExC_state_t *pRExC_state)
     regex_charset cs;
     bool has_use_defaults = FALSE;
     const char* const seqstart = RExC_parse - 1; /* Point to the '?' */
+    int x_mod_count = 0;
 
     PERL_ARGS_ASSERT_PARSE_LPAREN_QUESTION_FLAGS;
 
@@ -9280,7 +9588,7 @@ S_parse_lparen_question_flags(pTHX_ RExC_state_t *pRExC_state)
         switch (*RExC_parse) {
 
             /* Code for the imsx flags */
-            CASE_STD_PMMOD_FLAGS_PARSE_SET(flagsp);
+            CASE_STD_PMMOD_FLAGS_PARSE_SET(flagsp, x_mod_count);
 
             case LOCALE_PAT_MOD:
                 if (has_charset_modifier) {
@@ -9350,15 +9658,15 @@ S_parse_lparen_question_flags(pTHX_ RExC_state_t *pRExC_state)
                 else {
                     vFAIL3("Regexp modifiers \"%c\" and \"%c\" are mutually exclusive", has_charset_modifier, *(RExC_parse - 1));
                 }
-                /*NOTREACHED*/
+                NOT_REACHED; /*NOTREACHED*/
             neg_modifier:
                 RExC_parse++;
                 vFAIL2("Regexp modifier \"%c\" may not appear after the \"-\"",
                                     *(RExC_parse - 1));
-                /*NOTREACHED*/
+                NOT_REACHED; /*NOTREACHED*/
             case ONCE_PAT_MOD: /* 'o' */
             case GLOBAL_PAT_MOD: /* 'g' */
-                if (SIZE_ONLY && ckWARN(WARN_REGEXP)) {
+                if (PASS2 && ckWARN(WARN_REGEXP)) {
                     const I32 wflagbit = *RExC_parse == 'o'
                                          ? WASTED_O
                                          : WASTED_G;
@@ -9378,7 +9686,7 @@ S_parse_lparen_question_flags(pTHX_ RExC_state_t *pRExC_state)
                 break;
 
             case CONTINUE_PAT_MOD: /* 'c' */
-                if (SIZE_ONLY && ckWARN(WARN_REGEXP)) {
+                if (PASS2 && ckWARN(WARN_REGEXP)) {
                     if (! (wastedflags & WASTED_C) ) {
                         wastedflags |= WASTED_GC;
                        /* diag_listed_as: Useless (?-%s) - don't use /%s modifier in regex; marked by <-- HERE in m/%s/ */
@@ -9393,7 +9701,7 @@ S_parse_lparen_question_flags(pTHX_ RExC_state_t *pRExC_state)
                 break;
             case KEEPCOPY_PAT_MOD: /* 'p' */
                 if (flagsp == &negflags) {
-                    if (SIZE_ONLY)
+                    if (PASS2)
                         ckWARNreg(RExC_parse + 1,"Useless use of (?-p)");
                 } else {
                     *flagsp |= RXf_PMf_KEEPCOPY;
@@ -9417,6 +9725,9 @@ S_parse_lparen_question_flags(pTHX_ RExC_state_t *pRExC_state)
                 if (RExC_flags & RXf_PMf_FOLD) {
                     RExC_contains_i = 1;
                 }
+                if (PASS2) {
+                    STD_PMMOD_FLAGS_PARSE_X_WARN(x_mod_count);
+                }
                 return;
                 /*NOTREACHED*/
             default:
@@ -9425,11 +9736,15 @@ S_parse_lparen_question_flags(pTHX_ RExC_state_t *pRExC_state)
                /* diag_listed_as: Sequence (?%s...) not recognized in regex; marked by <-- HERE in m/%s/ */
                 vFAIL2utf8f("Sequence (%"UTF8f"...) not recognized",
                       UTF8fARG(UTF, RExC_parse-seqstart, seqstart));
-                /*NOTREACHED*/
+                NOT_REACHED; /*NOTREACHED*/
         }
 
         ++RExC_parse;
     }
+
+    if (PASS2) {
+        STD_PMMOD_FLAGS_PARSE_X_WARN(x_mod_count);
+    }
 }
 
 /*
@@ -9669,7 +9984,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                 /* diag_listed_as: Sequence (?%s...) not recognized in regex; marked by <-- HERE in m/%s/ */
                vFAIL3("Sequence (%.*s...) not recognized",
                                 RExC_parse-seqstart, seqstart);
-               /*NOTREACHED*/
+               NOT_REACHED; /*NOTREACHED*/
             case '<':           /* (?<...) */
                if (*RExC_parse == '!')
                    paren = ',';
@@ -9802,7 +10117,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                 if (RExC_parse == RExC_end || *RExC_parse != ')')
                     vFAIL("Sequence (?&... not terminated");
                 goto gen_recurse_regop;
-                assert(0); /* NOT REACHED */
+                /* NOT REACHED */
             case '+':
                 if (!(RExC_parse[0] >= '1' && RExC_parse[0] <= '9')) {
                     RExC_parse++;
@@ -9860,21 +10175,19 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                     num = RExC_npar + num - 1;
                 }
 
-                ret = reganode(pRExC_state, GOSUB, num);
+                ret = reg2Lanode(pRExC_state, GOSUB, num, RExC_recurse_count);
                 if (!SIZE_ONLY) {
                    if (num > (I32)RExC_rx->nparens) {
                        RExC_parse++;
                        vFAIL("Reference to nonexistent group");
                    }
-                   ARG2L_SET( ret, RExC_recurse_count++);
-                    RExC_emit++;
+                   RExC_recurse_count++;
                    DEBUG_OPTIMISE_MORE_r(PerlIO_printf(Perl_debug_log,
-                       "Recurse #%"UVuf" to %"IVdf"\n",
+                        "%*s%*s Recurse #%"UVuf" to %"IVdf"\n",
+                              22, "|    |", (int)(depth * 2 + 1), "",
                               (UV)ARG(ret), (IV)ARG2L(ret)));
-               } else {
-                   RExC_size++;
-               }
-                    RExC_seen |= REG_RECURSE_SEEN;
+                }
+                RExC_seen |= REG_RECURSE_SEEN;
                 Set_Node_Length(ret, 1 + regarglen[OP(ret)]); /* MJD */
                Set_Node_Offset(ret, parse_start); /* MJD */
 
@@ -9882,7 +10195,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                 nextchar(pRExC_state);
                 return ret;
 
-            assert(0); /* NOT REACHED */
+            /* NOT REACHED */
 
            case '?':           /* (??...) */
                is_logical = 1;
@@ -9892,7 +10205,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                     vFAIL2utf8f(
                         "Sequence (%"UTF8f"...) not recognized",
                         UTF8fARG(UTF, RExC_parse-seqstart, seqstart));
-                   /*NOTREACHED*/
+                   NOT_REACHED; /*NOTREACHED*/
                }
                *flagp |= POSTPONED;
                paren = *RExC_parse++;
@@ -9937,17 +10250,22 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                if (is_logical) {
                     regnode *eval;
                    ret = reg_node(pRExC_state, LOGICAL);
-                    eval = reganode(pRExC_state, EVAL, n);
+
+                    eval = reg2Lanode(pRExC_state, EVAL,
+                                       n,
+
+                                       /* for later propagation into (??{})
+                                        * return value */
+                                       RExC_flags & RXf_PMf_COMPILETIME
+                                      );
                    if (!SIZE_ONLY) {
                        ret->flags = 2;
-                        /* for later propagation into (??{}) return value */
-                        eval->flags = (U8) (RExC_flags & RXf_PMf_COMPILETIME);
                     }
                     REGTAIL(pRExC_state, ret, eval);
                     /* deal with the length of this later - MJD */
                    return ret;
                }
-               ret = reganode(pRExC_state, EVAL, n);
+               ret = reg2Lanode(pRExC_state, EVAL, n, 0);
                Set_Node_Length(ret, RExC_parse - parse_start + 1);
                Set_Node_Offset(ret, parse_start);
                return ret;
@@ -9955,6 +10273,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
            case '(':           /* (?(?{...})...) and (?(?=...)...) */
            {
                int is_define= 0;
+                const int DEFINE_len = sizeof("DEFINE") - 1;
                if (RExC_parse[0] == '?') {        /* (?(?...)) */
                    if (RExC_parse[1] == '=' || RExC_parse[1] == '!'
                        || RExC_parse[1] == '<'
@@ -9997,15 +10316,11 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                     ret = reganode(pRExC_state,NGROUPP,num);
                     goto insert_if_check_paren;
                }
-               else if (RExC_parse[0] == 'D' &&
-                        RExC_parse[1] == 'E' &&
-                        RExC_parse[2] == 'F' &&
-                        RExC_parse[3] == 'I' &&
-                        RExC_parse[4] == 'N' &&
-                        RExC_parse[5] == 'E')
-               {
+               else if (strnEQ(RExC_parse, "DEFINE",
+                                       MIN(DEFINE_len, RExC_end - RExC_parse)))
+                {
                    ret = reganode(pRExC_state,DEFINEP,0);
-                   RExC_parse +=;
+                   RExC_parse += DEFINE_len;
                    is_define = 1;
                    goto insert_if_check_paren;
                }
@@ -10084,8 +10399,12 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                    }
                    else
                        lastbr = NULL;
-                   if (c != ')')
-                       vFAIL("Switch (?(condition)... contains too many branches");
+                    if (c != ')') {
+                        if (RExC_parse>RExC_end)
+                            vFAIL("Switch (?(condition)... not terminated");
+                        else
+                            vFAIL("Switch (?(condition)... contains too many branches");
+                    }
                    ender = reg_node(pRExC_state, TAIL);
                     REGTAIL(pRExC_state, br, ender);
                    if (lastbr) {
@@ -10137,7 +10456,8 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
                    && !RExC_open_parens[parno-1])
                {
                    DEBUG_OPTIMISE_MORE_r(PerlIO_printf(Perl_debug_log,
-                       "Setting open paren #%"IVdf" to %d\n",
+                        "%*s%*s Setting open paren #%"IVdf" to %d\n",
+                        22, "|    |", (int)(depth * 2 + 1), "",
                        (IV)parno, REG_NODE_NUM(ret)));
                    RExC_open_parens[parno-1]= ret;
                }
@@ -10226,8 +10546,8 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
            ender = reganode(pRExC_state, CLOSE, parno);
             if (!SIZE_ONLY && RExC_seen & REG_RECURSE_SEEN) {
                DEBUG_OPTIMISE_MORE_r(PerlIO_printf(Perl_debug_log,
-                       "Setting close paren #%"IVdf" to %d\n",
-                       (IV)parno, REG_NODE_NUM(ender)));
+                        "%*s%*s Setting close paren #%"IVdf" to %d\n",
+                        22, "|    |", (int)(depth * 2 + 1), "", (IV)parno, REG_NODE_NUM(ender)));
                RExC_close_parens[parno-1]= ender;
                if (RExC_nestroot == parno)
                    RExC_nestroot = 0;
@@ -10253,15 +10573,13 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
            break;
        }
         DEBUG_PARSE_r(if (!SIZE_ONLY) {
-            SV * const mysv_val1=sv_newmortal();
-            SV * const mysv_val2=sv_newmortal();
             DEBUG_PARSE_MSG("lsbr");
-            regprop(RExC_rx, mysv_val1, lastbr, NULL);
-            regprop(RExC_rx, mysv_val2, ender, NULL);
+            regprop(RExC_rx, RExC_mysv1, lastbr, NULL, pRExC_state);
+            regprop(RExC_rx, RExC_mysv2, ender, NULL, pRExC_state);
             PerlIO_printf(Perl_debug_log, "~ tying lastbr %s (%"IVdf") to ender %s (%"IVdf") offset %"IVdf"\n",
-                          SvPV_nolen_const(mysv_val1),
+                          SvPV_nolen_const(RExC_mysv1),
                           (IV)REG_NODE_NUM(lastbr),
-                          SvPV_nolen_const(mysv_val2),
+                          SvPV_nolen_const(RExC_mysv2),
                           (IV)REG_NODE_NUM(ender),
                           (IV)(ender - lastbr)
             );
@@ -10294,15 +10612,13 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
             if (is_nothing) {
                 br= PL_regkind[OP(ret)] != BRANCH ? regnext(ret) : ret;
                 DEBUG_PARSE_r(if (!SIZE_ONLY) {
-                    SV * const mysv_val1=sv_newmortal();
-                    SV * const mysv_val2=sv_newmortal();
                     DEBUG_PARSE_MSG("NADA");
-                    regprop(RExC_rx, mysv_val1, ret, NULL);
-                    regprop(RExC_rx, mysv_val2, ender, NULL);
+                    regprop(RExC_rx, RExC_mysv1, ret, NULL, pRExC_state);
+                    regprop(RExC_rx, RExC_mysv2, ender, NULL, pRExC_state);
                     PerlIO_printf(Perl_debug_log, "~ converting ret %s (%"IVdf") to ender %s (%"IVdf") offset %"IVdf"\n",
-                                  SvPV_nolen_const(mysv_val1),
+                                  SvPV_nolen_const(RExC_mysv1),
                                   (IV)REG_NODE_NUM(ret),
-                                  SvPV_nolen_const(mysv_val2),
+                                  SvPV_nolen_const(RExC_mysv2),
                                   (IV)REG_NODE_NUM(ender),
                                   (IV)(ender - ret)
                     );
@@ -10355,7 +10671,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp,U32 depth)
        }
        else
            FAIL("Junk on end of regexp");      /* "Can't happen". */
-       assert(0); /* NOTREACHED */
+       NOT_REACHED; /* NOTREACHED */
     }
 
     if (RExC_in_lookbehind) {
@@ -10423,7 +10739,9 @@ S_regbranch(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, I32 first, U32 depth)
        if (chain == NULL)      /* First piece. */
            *flagp |= flags&SPSTART;
        else {
-           RExC_naughty++;
+           /* FIXME adding one for every branch after the first is probably
+            * excessive now we have TRIE support. (hv) */
+           MARK_NAUGHTY(1);
             REGTAIL(pRExC_state, chain, latest);
        }
        chain = latest;
@@ -10525,7 +10843,6 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
             if (max < min) {    /* If can't match, warn and optimize to fail
                                    unconditionally */
                 if (SIZE_ONLY) {
-                    ckWARNreg(RExC_parse, "Quantifier {n,m} with n > m can't match");
 
                     /* We can't back off the size because we have to reserve
                      * enough space for all the things we are about to throw
@@ -10534,6 +10851,7 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
                     RExC_size = PREVOPER(RExC_size) - regarglen[(U8)OPFAIL];
                 }
                 else {
+                    ckWARNreg(RExC_parse, "Quantifier {n,m} with n > m can't match");
                     RExC_emit = orig_emit;
                 }
                 ret = reg_node(pRExC_state, OPFAIL);
@@ -10543,7 +10861,7 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
                      && RExC_parse < RExC_end
                      && (*RExC_parse == '?' || *RExC_parse == '+'))
             {
-                if (SIZE_ONLY) {
+                if (PASS2) {
                     ckWARN2reg(RExC_parse + 1,
                                "Useless use of greediness modifier '%c'",
                                *RExC_parse);
@@ -10555,7 +10873,7 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
 
        do_curly:
            if ((flags&SIMPLE)) {
-               RExC_naughty += 2 + RExC_naughty / 2;
+                MARK_NAUGHTY_EXP(2, 2);
                reginsert(pRExC_state, CURLY, ret, depth+1);
                 Set_Node_Offset(ret, parse_start+1); /* MJD */
                 Set_Node_Cur_Length(ret, parse_start);
@@ -10581,7 +10899,7 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
                 REGTAIL(pRExC_state, ret, reg_node(pRExC_state, NOTHING));
                if (SIZE_ONLY)
                    RExC_whilem_seen++, RExC_extralen += 3;
-               RExC_naughty += 4 + RExC_naughty;       /* compound interest */
+                MARK_NAUGHTY_EXP(1, 4);     /* compound interest */
            }
            ret->flags = 0;
 
@@ -10631,7 +10949,7 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
     if (op == '*' && (flags&SIMPLE)) {
        reginsert(pRExC_state, STAR, ret, depth+1);
        ret->flags = 0;
-       RExC_naughty += 4;
+       MARK_NAUGHTY(4);
         RExC_seen |= REG_UNBOUNDED_QUANTIFIER_SEEN;
     }
     else if (op == '*') {
@@ -10641,7 +10959,7 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
     else if (op == '+' && (flags&SIMPLE)) {
        reginsert(pRExC_state, PLUS, ret, depth+1);
        ret->flags = 0;
-       RExC_naughty += 3;
+       MARK_NAUGHTY(3);
         RExC_seen |= REG_UNBOUNDED_QUANTIFIER_SEEN;
     }
     else if (op == '+') {
@@ -10689,10 +11007,9 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth)
     return(ret);
 }
 
-STATIC bool
+STATIC STRLEN
 S_grok_bslash_N(pTHX_ RExC_state_t *pRExC_state, regnode** node_p,
-                      UV *valuep, I32 *flagp, U32 depth, bool in_char_class,
-                      const bool strict   /* Apply stricter parsing rules? */
+                      UV *valuep, I32 *flagp, U32 depth, SV** substitute_parse
     )
 {
 
@@ -10700,46 +11017,75 @@ S_grok_bslash_N(pTHX_ RExC_state_t *pRExC_state, regnode** node_p,
    and needs to handle the rest. RExC_parse is expected to point at the first
    char following the N at the time of the call.  On successful return,
    RExC_parse has been updated to point to just after the sequence identified
-   by this routine, and <*flagp> has been updated.
-
-   The \N may be inside (indicated by the boolean <in_char_class>) or outside a
-   character class.
-
-   \N may begin either a named sequence, or if outside a character class, mean
-   to match a non-newline.  For non single-quoted regexes, the tokenizer has
-   attempted to decide which, and in the case of a named sequence, converted it
+   by this routine, <*flagp> has been updated, and the non-NULL input pointers
+   have been set appropriately.
+
+   The typical case for this is \N{some character name}.  This is usually
+   called while parsing the input, filling in or ready to fill in an EXACTish
+   node, and the code point for the character should be returned, so that it
+   can be added to the node, and parsing continued with the next input
+   character.  But it may be that instead of a single character the \N{}
+   expands to more than one, a named sequence.  In this case any following
+   quantifier applies to the whole sequence, and it is easier, given the code
+   structure that calls this, to handle it from a different area of the code.
+   For this reason, the input parameters can be set so that it returns valid
+   only on one or the other of these cases.
+
+   Another possibility is for the input to be an empty \N{}, which for
+   backwards compatibility we accept, but generate a NOTHING node which should
+   later get optimized out.  This is handled from the area of code which can
+   handle a named sequence, so if called with the parameters for the other, it
+   fails.
+
+   Still another possibility is for the \N to mean [^\n], and not a single
+   character or explicit sequence at all.  This is determined by context.
+   Again, this is handled from the area of code which can handle a named
+   sequence, so if called with the parameters for the other, it also fails.
+
+   And the final possibility is for the \N to be called from within a bracketed
+   character class.  In this case the [^\n] meaning makes no sense, and so is
+   an error.  Other anomalous situations are left to the calling code to handle.
+
+   For non-single-quoted regexes, the tokenizer has attempted to decide which
+   of the above applies, and in the case of a named sequence, has converted it
    into one of the forms: \N{} (if the sequence is null), or \N{U+c1.c2...},
    where c1... are the characters in the sequence.  For single-quoted regexes,
    the tokenizer passes the \N sequence through unchanged; this code will not
    attempt to determine this nor expand those, instead raising a syntax error.
    The net effect is that if the beginning of the passed-in pattern isn't '{U+'
    or there is no '}', it signals that this \N occurrence means to match a
-   non-newline.
+   non-newline. (This mostly was done because of [perl #56444].)
 
-   Only the \N{U+...} form should occur in a character class, for the same
-   reason that '.' inside a character class means to just match a period: it
-   just doesn't make sense.
+   The API is somewhat convoluted due to historical and the above reasons.
 
    The function raises an error (via vFAIL), and doesn't return for various
-   syntax errors.  Otherwise it returns TRUE and sets <node_p> or <valuep> on
-   success; it returns FALSE otherwise. Returns FALSE, setting *flagp to
-   RESTART_UTF8 if the sizing scan needs to be restarted. Such a restart is
-   only possible if node_p is non-NULL.
-
+   syntax errors.  For other failures, it returns (STRLEN) -1.  For successes,
+   it returns a count of how many characters were accounted for by it.  (This
+   can be 0 for \N{}; 1 for it meaning [^\n]; and otherwise the number of code
+   points in the sequence.  It sets <node_p>, <valuep>, and/or
+   <substitute_parse> on success.
 
    If <valuep> is non-null, it means the caller can accept an input sequence
-   consisting of a just a single code point; <*valuep> is set to that value
-   if the input is such.
-
-   If <node_p> is non-null it signifies that the caller can accept any other
-   legal sequence (i.e., one that isn't just a single code point).  <*node_p>
-   is set as follows:
-    1) \N means not-a-NL: points to a newly created REG_ANY node;
-    2) \N{}:              points to a new NOTHING node;
+   consisting of a just a single code point; <*valuep> is set to the value
+   of the only or first code point in the input.
+
+   If <substitute_parse> is non-null, it means the caller can accept an input
+   sequence consisting of one or more code points; <*substitute_parse> is a
+   newly created mortal SV* in this case, containing \x{} escapes representing
+   those code points.
+
+   Both <valuep> and <substitute_parse> can be non-NULL.
+
+   If <node_p> is non-null, <substitute_parse> must be NULL.  This signifies
+   that the caller can accept any legal sequence other than a single code
+   point.  To wit, <*node_p> is set as follows:
+    1) \N means not-a-NL: points to a newly created REG_ANY node; return is 1
+    2) \N{}:              points to a new NOTHING node; return is 0
     3) otherwise:         points to a new EXACT node containing the resolved
-                          string.
-   Note that FALSE is returned for single code point sequences if <valuep> is
-   null.
+                          string; return is the number of code points in the
+                          string.  This will never be 1.
+   Note that failure is returned for single code point sequences if <valuep> is
+   null and <node_p> is not.
  */
 
     char * endbrace;    /* '}' following the name */
@@ -10748,6 +11094,8 @@ S_grok_bslash_N(pTHX_ RExC_state_t *pRExC_state, regnode** node_p,
                            stream */
     bool has_multiple_chars; /* true if the input stream contains a sequence of
                                 more than one character */
+    bool in_char_class = substitute_parse != NULL;
+    STRLEN count = 0;   /* Number of characters in this sequence */
 
     GET_RE_DEBUG_FLAGS_DECL;
 
@@ -10756,6 +11104,7 @@ S_grok_bslash_N(pTHX_ RExC_state_t *pRExC_state, regnode** node_p,
     GET_RE_DEBUG_FLAGS;
 
     assert(cBOOL(node_p) ^ cBOOL(valuep));  /* Exactly one should be set */
+    assert(! (node_p && substitute_parse)); /* At most 1 should be set */
 
     /* The [^\n] meaning of \N ignores spaces and comments under the /x
      * modifier.  The other meaning does not, so use a temporary until we find
@@ -10774,16 +11123,16 @@ S_grok_bslash_N(pTHX_ RExC_state_t *pRExC_state, regnode** node_p,
             if (in_char_class) {
                 vFAIL("\\N in a character class must be a named character: \\N{...}");
             }
-            return FALSE;
+            return (STRLEN) -1;
         }
         RExC_parse--;   /* Need to back off so nextchar() doesn't skip the
                            current char */
        nextchar(pRExC_state);
        *node_p = reg_node(pRExC_state, REG_ANY);
        *flagp |= HASWIDTH|SIMPLE;
-       RExC_naughty++;
+       MARK_NAUGHTY(1);
         Set_Node_Length(*node_p, 1); /* MJD */
-       return TRUE;
+       return 1;
     }
 
     /* Here, we have decided it should be a named character or sequence */
@@ -10810,28 +11159,14 @@ S_grok_bslash_N(pTHX_ RExC_state_t *pRExC_state, regnode** node_p,
     }
 
     if (endbrace == RExC_parse) {   /* empty: \N{} */
-        bool ret = TRUE;
        if (node_p) {
            *node_p = reg_node(pRExC_state,NOTHING);
        }
-        else if (in_char_class) {
-            if (SIZE_ONLY && in_char_class) {
-                if (strict) {
-                    RExC_parse++;   /* Position after the "}" */
-                    vFAIL("Zero length \\N{}");
-                }
-                else {
-                    ckWARNreg(RExC_parse,
-                              "Ignoring zero length \\N{} in character class");
-                }
-            }
-            ret = FALSE;
-       }
-        else {
-            return FALSE;
+        else if (! in_char_class) {
+            return (STRLEN) -1;
         }
         nextchar(pRExC_state);
-        return ret;
+        return 0;
     }
 
     RExC_uni_semantics = 1; /* Unicode named chars imply Unicode semantics */
@@ -10843,90 +11178,103 @@ S_grok_bslash_N(pTHX_ RExC_state_t *pRExC_state, regnode** node_p,
      * point, and is terminated by the brace */
     has_multiple_chars = (endchar < endbrace);
 
-    if (valuep && (! has_multiple_chars || in_char_class)) {
-       /* We only pay attention to the first char of
-        multichar strings being returned in char classes. I kinda wonder
-       if this makes sense as it does change the behaviour
-       from earlier versions, OTOH that behaviour was broken
-       as well. XXX Solution is to recharacterize as
-       [rest-of-class]|multi1|multi2... */
-
+    /* We get the first code point if we want it, and either there is only one,
+     * or we can accept both cases of one and more than one */
+    if (valuep && (substitute_parse || ! has_multiple_chars)) {
        STRLEN length_of_hex = (STRLEN)(endchar - RExC_parse);
        I32 grok_hex_flags = PERL_SCAN_ALLOW_UNDERSCORES
-           | PERL_SCAN_DISALLOW_PREFIX
-           | (SIZE_ONLY ? PERL_SCAN_SILENT_ILLDIGIT : 0);
+                           | PERL_SCAN_DISALLOW_PREFIX
+
+                             /* No errors in the first pass (See [perl
+                              * #122671].)  We let the code below find the
+                              * errors when there are multiple chars. */
+                           | ((SIZE_ONLY || has_multiple_chars)
+                              ? PERL_SCAN_SILENT_ILLDIGIT
+                              : 0);
 
        *valuep = grok_hex(RExC_parse, &length_of_hex, &grok_hex_flags, NULL);
 
        /* The tokenizer should have guaranteed validity, but it's possible to
-        * bypass it by using single quoting, so check */
-       if (length_of_hex == 0
-           || length_of_hex != (STRLEN)(endchar - RExC_parse) )
-       {
-           RExC_parse += length_of_hex;        /* Includes all the valid */
-           RExC_parse += (RExC_orig_utf8)      /* point to after 1st invalid */
-                           ? UTF8SKIP(RExC_parse)
-                           : 1;
-           /* Guard against malformed utf8 */
-           if (RExC_parse >= endchar) {
-                RExC_parse = endchar;
+         * bypass it by using single quoting, so check.  Don't do the check
+         * here when there are multiple chars; we do it below anyway. */
+        if (! has_multiple_chars) {
+            if (length_of_hex == 0
+                || length_of_hex != (STRLEN)(endchar - RExC_parse) )
+            {
+                RExC_parse += length_of_hex;   /* Includes all the valid */
+                RExC_parse += (RExC_orig_utf8) /* point to after 1st invalid */
+                                ? UTF8SKIP(RExC_parse)
+                                : 1;
+                /* Guard against malformed utf8 */
+                if (RExC_parse >= endchar) {
+                    RExC_parse = endchar;
+                }
+                vFAIL("Invalid hexadecimal number in \\N{U+...}");
             }
-           vFAIL("Invalid hexadecimal number in \\N{U+...}");
-       }
 
-        if (in_char_class && has_multiple_chars) {
-            if (strict) {
-                RExC_parse = endbrace;
-                vFAIL("\\N{} in character class restricted to one character");
-            }
-            else {
-                ckWARNreg(endchar, "Using just the first character returned by \\N{} in character class");
-            }
+            RExC_parse = endbrace + 1;
+            return 1;
         }
-
-        RExC_parse = endbrace + 1;
     }
-    else if (! node_p || ! has_multiple_chars) {
 
-        /* Here, the input is legal, but not according to the caller's
-         * options.  We fail without advancing the parse, so that the
-         * caller can try again */
+    /* Here, we should have already handled the case where a single character
+     * is expected and found.  So it is a failure if we aren't expecting
+     * multiple chars and got them; or didn't get them but wanted them.  We
+     * fail without advancing the parse, so that the caller can try again with
+     * different acceptance criteria */
+    if ((! node_p && ! substitute_parse) || ! has_multiple_chars) {
         RExC_parse = p;
-        return FALSE;
+        return (STRLEN) -1;
     }
-    else {
+
+    {
 
        /* What is done here is to convert this to a sub-pattern of the form
-        * (?:\x{char1}\x{char2}...)
-        * and then call reg recursively.  That way, it retains its atomicness,
-        * while not having to worry about special handling that some code
-        * points may have.  toke.c has converted the original Unicode values
-        * to native, so that we can just pass on the hex values unchanged.  We
-        * do have to set a flag to keep recoding from happening in the
-        * recursion */
-
-       SV * substitute_parse = newSVpvn_flags("?:", 2, SVf_UTF8|SVs_TEMP);
+        * \x{char1}\x{char2}...
+         * and then either return it in <*substitute_parse> if non-null; or
+         * call reg recursively to parse it (enclosing in "(?: ... )" ).  That
+         * way, it retains its atomicness, while not having to worry about
+         * special handling that some code points may have.  toke.c has
+         * converted the original Unicode values to native, so that we can just
+         * pass on the hex values unchanged.  We do have to set a flag to keep
+         * recoding from happening in the recursion */
+
+       SV * dummy = NULL;
        STRLEN len;
        char *orig_end = RExC_end;
         I32 flags;
 
+        if (substitute_parse) {
+            *substitute_parse = newSVpvs("");
+        }
+        else {
+            substitute_parse = &dummy;
+            *substitute_parse = newSVpvs("?:");
+        }
+        *substitute_parse = sv_2mortal(*substitute_parse);
+
        while (RExC_parse < endbrace) {
 
            /* Convert to notation the rest of the code understands */
-           sv_catpv(substitute_parse, "\\x{");
-           sv_catpvn(substitute_parse, RExC_parse, endchar - RExC_parse);
-           sv_catpv(substitute_parse, "}");
+           sv_catpv(*substitute_parse, "\\x{");
+           sv_catpvn(*substitute_parse, RExC_parse, endchar - RExC_parse);
+           sv_catpv(*substitute_parse, "}");
 
            /* Point to the beginning of the next character in the sequence. */
            RExC_parse = endchar + 1;
            endchar = RExC_parse + strcspn(RExC_parse, ".}");
+
+            count++;
        }
-       sv_catpv(substitute_parse, ")");
+        if (! in_char_class) {
+            sv_catpv(*substitute_parse, ")");
+        }
 
-       RExC_parse = SvPV(substitute_parse, len);
+       RExC_parse = SvPV(*substitute_parse, len);
 
        /* Don't allow empty number */
-       if (len < 8) {
+       if (len < (STRLEN) ((substitute_parse) ? 6 : 8)) {
+            RExC_parse = endbrace;
            vFAIL("Invalid hexadecimal number in \\N{U+...}");
        }
        RExC_end = RExC_parse + len;
@@ -10934,15 +11282,17 @@ S_grok_bslash_N(pTHX_ RExC_state_t *pRExC_state, regnode** node_p,
        /* The values are Unicode, and therefore not subject to recoding */
        RExC_override_recoding = 1;
 
-       if (!(*node_p = reg(pRExC_state, 1, &flags, depth+1))) {
-            if (flags & RESTART_UTF8) {
-                *flagp = RESTART_UTF8;
-                return FALSE;
+        if (node_p) {
+            if (!(*node_p = reg(pRExC_state, 1, &flags, depth+1))) {
+                if (flags & RESTART_UTF8) {
+                    *flagp = RESTART_UTF8;
+                    return (STRLEN) -1;
+                }
+                FAIL2("panic: reg returned NULL to grok_bslash_N, flags=%#"UVxf"",
+                    (UV) flags);
             }
-            FAIL2("panic: reg returned NULL to grok_bslash_N, flags=%#"UVxf"",
-                  (UV) flags);
+            *flagp |= flags&(HASWIDTH|SPSTART|SIMPLE|POSTPONED);
         }
-       *flagp |= flags&(HASWIDTH|SPSTART|SIMPLE|POSTPONED);
 
        RExC_parse = endbrace;
        RExC_end = orig_end;
@@ -10951,7 +11301,7 @@ S_grok_bslash_N(pTHX_ RExC_state_t *pRExC_state, regnode** node_p,
         nextchar(pRExC_state);
     }
 
-    return TRUE;
+    return count;
 }
 
 
@@ -11053,19 +11403,25 @@ S_alloc_maybe_populate_EXACT(pTHX_ RExC_state_t *pRExC_state,
 
     if (! len_passed_in) {
         if (UTF) {
-            if (UNI_IS_INVARIANT(code_point)) {
+            if (UVCHR_IS_INVARIANT(code_point)) {
                 if (LOC || ! FOLD) {    /* /l defers folding until runtime */
                     *character = (U8) code_point;
                 }
-                else { /* Here is /i and not /l (toFOLD() is defined on just
+                else { /* Here is /i and not /l. (toFOLD() is defined on just
                           ASCII, which isn't the same thing as INVARIANT on
                           EBCDIC, but it works there, as the extra invariants
                           fold to themselves) */
                     *character = toFOLD((U8) code_point);
-                    if (downgradable
-                        && *character == code_point
-                        && ! HAS_NONLATIN1_FOLD_CLOSURE(code_point))
-                    {
+
+                    /* We can downgrade to an EXACT node if this character
+                     * isn't a folding one.  Note that this assumes that
+                     * nothing above Latin1 folds to some other invariant than
+                     * one of these alphabetics; otherwise we would also have
+                     * to check:
+                     *  && (! HAS_NONLATIN1_FOLD_CLOSURE(code_point)
+                     *      || ASCII_FOLD_RESTRICTED))
+                     */
+                    if (downgradable && PL_fold[code_point] == code_point) {
                         OP(node) = EXACT;
                     }
                 }
@@ -11082,7 +11438,10 @@ S_alloc_maybe_populate_EXACT(pTHX_ RExC_state_t *pRExC_state,
                                                       ? FOLD_FLAGS_NOMIX_ASCII
                                                       : 0));
                 if (downgradable
-                    && folded == code_point
+                    && folded == code_point /* This quickly rules out many
+                                               cases, avoiding the
+                                               _invlist_contains_cp() overhead
+                                               for those.  */
                     && ! _invlist_contains_cp(PL_utf8_foldable, code_point))
                 {
                     OP(node) = EXACT;
@@ -11267,10 +11626,8 @@ tryagain:
        nextchar(pRExC_state);
        if (RExC_flags & RXf_PMf_MULTILINE)
            ret = reg_node(pRExC_state, MBOL);
-       else if (RExC_flags & RXf_PMf_SINGLELINE)
-           ret = reg_node(pRExC_state, SBOL);
        else
-           ret = reg_node(pRExC_state, BOL);
+           ret = reg_node(pRExC_state, SBOL);
         Set_Node_Length(ret, 1); /* MJD */
        break;
     case '$':
@@ -11279,10 +11636,8 @@ tryagain:
            RExC_seen_zerolen++;
        if (RExC_flags & RXf_PMf_MULTILINE)
            ret = reg_node(pRExC_state, MEOL);
-       else if (RExC_flags & RXf_PMf_SINGLELINE)
-           ret = reg_node(pRExC_state, SEOL);
        else
-           ret = reg_node(pRExC_state, EOL);
+           ret = reg_node(pRExC_state, SEOL);
         Set_Node_Length(ret, 1); /* MJD */
        break;
     case '.':
@@ -11292,7 +11647,7 @@ tryagain:
        else
            ret = reg_node(pRExC_state, REG_ANY);
        *flagp |= HASWIDTH|SIMPLE;
-       RExC_naughty++;
+       MARK_NAUGHTY(1);
         Set_Node_Length(ret, 1); /* MJD */
        break;
     case '[':
@@ -11371,6 +11726,11 @@ tryagain:
        case 'A':
            RExC_seen_zerolen++;
            ret = reg_node(pRExC_state, SBOL);
+            /* SBOL is shared with /^/ so we set the flags so we can tell
+             * /\A/ from /^/ in split. We check ret because first pass we
+             * have no regop struct to set the flags on. */
+            if (PASS2)
+                ret->flags = 1;
            *flagp |= SIMPLE;
            goto finish_meta_pat;
        case 'G':
@@ -11402,7 +11762,7 @@ tryagain:
            ret = reg_node(pRExC_state, CANY);
             RExC_seen |= REG_CANY_SEEN;
            *flagp |= HASWIDTH|SIMPLE;
-            if (SIZE_ONLY) {
+            if (PASS2) {
                 ckWARNdep(RExC_parse+1, "\\C is deprecated");
             }
            goto finish_meta_pat;
@@ -11431,7 +11791,7 @@ tryagain:
            ret = reg_node(pRExC_state, op);
            FLAGS(ret) = get_regex_charset(RExC_flags);
            *flagp |= SIMPLE;
-           if (! SIZE_ONLY && (U8) *(RExC_parse + 1) == '{') {
+           if ((U8) *(RExC_parse + 1) == '{') {
                 /* diag_listed_as: Use "%s" instead of "%s" */
                vFAIL("Use \"\\b\\{\" instead of \"\\b{\"");
            }
@@ -11449,7 +11809,7 @@ tryagain:
            ret = reg_node(pRExC_state, op);
            FLAGS(ret) = get_regex_charset(RExC_flags);
            *flagp |= SIMPLE;
-           if (! SIZE_ONLY && (U8) *(RExC_parse + 1) == '{') {
+           if ((U8) *(RExC_parse + 1) == '{') {
                 /* diag_listed_as: Use "%s" instead of "%s" */
                vFAIL("Use \"\\B\\{\" instead of \"\\B{\"");
            }
@@ -11558,8 +11918,9 @@ tryagain:
              * special treatment for quantifiers is not needed for such single
              * character sequences */
             ++RExC_parse;
-            if (! grok_bslash_N(pRExC_state, &ret, NULL, flagp, depth, FALSE,
-                                FALSE /* not strict */ )) {
+            if ((STRLEN) -1 == grok_bslash_N(pRExC_state, &ret, NULL, flagp,
+                                             depth, FALSE))
+            {
                 if (*flagp & RESTART_UTF8)
                     return NULL;
                 RExC_parse--;
@@ -11860,10 +12221,12 @@ tryagain:
                          * point sequence.  Handle those in the switch() above
                          * */
                         RExC_parse = p + 1;
-                        if (! grok_bslash_N(pRExC_state, NULL, &ender,
-                                            flagp, depth, FALSE,
-                                            FALSE /* not strict */ ))
-                        {
+                        if ((STRLEN) -1 == grok_bslash_N(pRExC_state, NULL,
+                                                         &ender,
+                                                         flagp,
+                                                         depth,
+                                                         FALSE
+                        )) {
                             if (*flagp & RESTART_UTF8)
                                 FAIL("panic: grok_bslash_N set RESTART_UTF8");
                             RExC_parse = p = oldp;
@@ -11887,11 +12250,11 @@ tryagain:
                        p++;
                        break;
                    case 'e':
-                         ender = ASCII_TO_NATIVE('\033');
+                       ender = ESC_NATIVE;
                        p++;
                        break;
                    case 'a':
-                         ender = '\a';
+                       ender = '\a';
                        p++;
                        break;
                    case 'o':
@@ -11902,7 +12265,7 @@ tryagain:
                            bool valid = grok_bslash_o(&p,
                                                       &result,
                                                       &error_msg,
-                                                      TRUE, /* out warnings */
+                                                      PASS2, /* out warnings */
                                                        FALSE, /* not strict */
                                                        TRUE, /* Output warnings
                                                                 for non-
@@ -11914,7 +12277,7 @@ tryagain:
                                vFAIL(error_msg);
                            }
                             ender = result;
-                           if (PL_encoding && ender < 0x100) {
+                           if (IN_ENCODING && ender < 0x100) {
                                goto recode_encoding;
                            }
                            if (ender > 0xff) {
@@ -11931,7 +12294,7 @@ tryagain:
                            bool valid = grok_bslash_x(&p,
                                                       &result,
                                                       &error_msg,
-                                                      TRUE, /* out warnings */
+                                                      PASS2, /* out warnings */
                                                        FALSE, /* not strict */
                                                        TRUE, /* Output warnings
                                                                 for non-
@@ -11944,7 +12307,7 @@ tryagain:
                            }
                             ender = result;
 
-                           if (PL_encoding && ender < 0x100) {
+                           if (IN_ENCODING && ender < 0x100) {
                                goto recode_encoding;
                            }
                            if (ender > 0xff) {
@@ -11954,7 +12317,7 @@ tryagain:
                        }
                    case 'c':
                        p++;
-                       ender = grok_bslash_c(*p++, SIZE_ONLY);
+                       ender = grok_bslash_c(*p++, PASS2);
                        break;
                     case '8': case '9': /* must be a backreference */
                         --p;
@@ -11993,7 +12356,7 @@ tryagain:
                                REQUIRE_UTF8;
                            }
                            p += numlen;
-                            if (SIZE_ONLY   /* like \08, \178 */
+                            if (PASS2   /* like \08, \178 */
                                 && numlen < 3
                                 && p < RExC_end
                                 && isDIGIT(*p) && ckWARN(WARN_REGEXP))
@@ -12003,14 +12366,14 @@ tryagain:
                                          form_short_octal_warning(p, numlen));
                             }
                        }
-                       if (PL_encoding && ender < 0x100)
+                       if (IN_ENCODING && ender < 0x100)
                            goto recode_encoding;
                        break;
                    recode_encoding:
                        if (! RExC_override_recoding) {
-                           SV* enc = PL_encoding;
+                           SV* enc = _get_encoding();
                            ender = reg_recode((const char)(U8)ender, &enc);
-                           if (!enc && SIZE_ONLY)
+                           if (!enc && PASS2)
                                ckWARNreg(p, "Invalid escape in the specified encoding");
                            REQUIRE_UTF8;
                        }
@@ -12127,9 +12490,8 @@ tryagain:
                             && (PL_fold[ender] != PL_fold_latin1[ender]
                                 || ender == LATIN_SMALL_LETTER_SHARP_S
                                 || (len > 0
-                                   && isARG2_lower_or_UPPER_ARG1('s', ender)
-                                   && isARG2_lower_or_UPPER_ARG1('s',
-                                                                 *(s-1)))))
+                                   && isALPHA_FOLD_EQ(ender, 's')
+                                   && isALPHA_FOLD_EQ(*(s-1), 's'))))
                         {
                             maybe_exactfu = FALSE;
                         }
@@ -12150,7 +12512,7 @@ tryagain:
                      * the simple case just below.) */
 
                     UV folded;
-                    if (isASCII(ender)) {
+                    if (isASCII_uni(ender)) {
                         folded = toFOLD(ender);
                         *(s)++ = (U8) folded;
                     }
@@ -12313,7 +12675,7 @@ tryagain:
                      * as if it turns into an EXACTFU, it could later get
                      * joined with another 's' that would then wrongly match
                      * the sharp s */
-                    if (maybe_exactfu && isARG2_lower_or_UPPER_ARG1('s', ender))
+                    if (maybe_exactfu && isALPHA_FOLD_EQ(ender, 's'))
                     {
                         maybe_exactfu = FALSE;
                     }
@@ -12462,22 +12824,24 @@ S_populate_ANYOF_from_invlist(pTHX_ regnode *node, SV** invlist_ptr)
            UV high;
            int i;
 
-            if (end == UV_MAX && start <= 256) {
-                ANYOF_FLAGS(node) |= ANYOF_ABOVE_LATIN1_ALL;
+            if (end == UV_MAX && start <= NUM_ANYOF_CODE_POINTS) {
+                ANYOF_FLAGS(node) |= ANYOF_MATCHES_ALL_ABOVE_BITMAP;
             }
-            else if (end >= 256) {
-                ANYOF_FLAGS(node) |= ANYOF_UTF8;
+            else if (end >= NUM_ANYOF_CODE_POINTS) {
+                ANYOF_FLAGS(node) |= ANYOF_HAS_UTF8_NONBITMAP_MATCHES;
             }
 
            /* Quit if are above what we should change */
-           if (start > 255) {
+           if (start >= NUM_ANYOF_CODE_POINTS) {
                break;
            }
 
            change_invlist = TRUE;
 
            /* Set all the bits in the range, up to the max that we are doing */
-           high = (end < 255) ? end : 255;
+           high = (end < NUM_ANYOF_CODE_POINTS - 1)
+                   ? end
+                   : NUM_ANYOF_CODE_POINTS - 1;
            for (i = start; i <= (int) high; i++) {
                if (! ANYOF_BITMAP_TEST(node, i)) {
                    ANYOF_BITMAP_SET(node, i);
@@ -12487,13 +12851,13 @@ S_populate_ANYOF_from_invlist(pTHX_ regnode *node, SV** invlist_ptr)
        invlist_iterfinish(*invlist_ptr);
 
         /* Done with loop; remove any code points that are in the bitmap from
-         * *invlist_ptr; similarly for code points above latin1 if we have a
-         * flag to match all of them anyways */
+         * *invlist_ptr; similarly for code points above the bitmap if we have
+         * flag to match all of them anyways */
        if (change_invlist) {
-           _invlist_subtract(*invlist_ptr, PL_Latin1, invlist_ptr);
+           _invlist_subtract(*invlist_ptr, PL_InBitmap, invlist_ptr);
        }
-        if (ANYOF_FLAGS(node) & ANYOF_ABOVE_LATIN1_ALL) {
-           _invlist_intersection(*invlist_ptr, PL_Latin1, invlist_ptr);
+        if (ANYOF_FLAGS(node) & ANYOF_MATCHES_ALL_ABOVE_BITMAP) {
+           _invlist_intersection(*invlist_ptr, PL_InBitmap, invlist_ptr);
        }
 
        /* If have completely emptied it, remove it completely */
@@ -12743,9 +13107,7 @@ S_handle_regex_sets(pTHX_ RExC_state_t *pRExC_state, SV** return_invlist,
      * upon an unescaped ']' that isn't one ending a regclass.  To do both
      * these things, we need to realize that something preceded by a backslash
      * is escaped, so we have to keep track of backslashes */
-    if (SIZE_ONLY) {
-        UV depth = 0; /* how many nested (?[...]) constructs */
-
+    if (PASS2) {
         Perl_ck_warner_d(aTHX_
             packWARN(WARN_EXPERIMENTAL__REGEX_SETS),
             "The regex_sets feature is experimental" REPORT_LOCATION,
@@ -12753,6 +13115,9 @@ S_handle_regex_sets(pTHX_ RExC_state_t *pRExC_state, SV** return_invlist,
                 UTF8fARG(UTF,
                          RExC_end - RExC_start - (RExC_parse - RExC_precomp),
                          RExC_precomp + (RExC_parse - RExC_precomp)));
+    }
+    else {
+        UV depth = 0; /* how many nested (?[...]) constructs */
 
         while (RExC_parse < RExC_end) {
             SV* current = NULL;
@@ -13253,11 +13618,60 @@ S_add_above_Latin1_folds(pTHX_ RExC_state_t *pRExC_state, const U8 cp, SV** invl
         default:
             /* Use deprecated warning to increase the chances of this being
              * output */
-            ckWARN2reg_d(RExC_parse, "Perl folding rules are not up-to-date for 0x%02X; please use the perlbug utility to report;", cp);
+            if (PASS2) {
+                ckWARN2reg_d(RExC_parse, "Perl folding rules are not up-to-date for 0x%02X; please use the perlbug utility to report;", cp);
+            }
             break;
     }
 }
 
+STATIC AV *
+S_add_multi_match(pTHX_ AV* multi_char_matches, SV* multi_string, const STRLEN cp_count)
+{
+    /* This adds the string scalar <multi_string> to the array
+     * <multi_char_matches>.  <multi_string> is known to have exactly
+     * <cp_count> code points in it.  This is used when constructing a
+     * bracketed character class and we find something that needs to match more
+     * than a single character.
+     *
+     * <multi_char_matches> is actually an array of arrays.  Each top-level
+     * element is an array that contains all the strings known so far that are
+     * the same length.  And that length (in number of code points) is the same
+     * as the index of the top-level array.  Hence, the [2] element is an
+     * array, each element thereof is a string containing TWO code points;
+     * while element [3] is for strings of THREE characters, and so on.  Since
+     * this is for multi-char strings there can never be a [0] nor [1] element.
+     *
+     * When we rewrite the character class below, we will do so such that the
+     * longest strings are written first, so that it prefers the longest
+     * matching strings first.  This is done even if it turns out that any
+     * quantifier is non-greedy, out of this programmer's (khw) laziness.  Tom
+     * Christiansen has agreed that this is ok.  This makes the test for the
+     * ligature 'ffi' come before the test for 'ff', for example */
+
+    AV* this_array;
+    AV** this_array_ptr;
+
+    PERL_ARGS_ASSERT_ADD_MULTI_MATCH;
+
+    if (! multi_char_matches) {
+        multi_char_matches = newAV();
+    }
+
+    if (av_exists(multi_char_matches, cp_count)) {
+        this_array_ptr = (AV**) av_fetch(multi_char_matches, cp_count, FALSE);
+        this_array = *this_array_ptr;
+    }
+    else {
+        this_array = newAV();
+        av_store(multi_char_matches, cp_count,
+                 (SV*) this_array);
+    }
+    av_push(this_array, multi_string);
+
+    return multi_char_matches;
+}
+
 /* The names of properties whose definitions are not known at compile time are
  * stored in this SV, after a constant heading.  So if the length has been
  * changed since initialization, then there is a run-time definition. */
@@ -13289,11 +13703,11 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
      * ignored in the recursion by means of a flag:
      * <RExC_in_multi_char_class>.)
      *
-     * ANYOF nodes contain a bit map for the first 256 characters, with the
-     * corresponding bit set if that character is in the list.  For characters
-     * above 255, a range list or swash is used.  There are extra bits for \w,
-     * etc. in locale ANYOFs, as what these match is not determinable at
-     * compile time
+     * ANYOF nodes contain a bit map for the first NUM_ANYOF_CODE_POINTS
+     * characters, with the corresponding bit set if that character is in the
+     * list.  For characters above this, a range list or swash is used.  There
+     * are extra bits for \w, etc. in locale ANYOFs, as what these match is not
+     * determinable at compile time
      *
      * Returns NULL, setting *flagp to RESTART_UTF8 if the sizing scan needs
      * to be restarted.  This can only happen if ret_invlist is non-NULL.
@@ -13363,6 +13777,11 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
     /* In a range, counts how many 0-2 of the ends of it came from literals,
      * not escapes.  Thus we can tell if 'A' was input vs \x{C1} */
     UV literal_endpoint = 0;
+
+    /* Is the range unicode? which means on a platform that isn't 1-1 native
+     * to Unicode (i.e. non-ASCII), each code point in it should be considered
+     * to be a Unicode value.  */
+    bool unicode_range = FALSE;
 #endif
     bool invert = FALSE;    /* Is this class to be complemented */
 
@@ -13407,7 +13826,7 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
        RExC_parse++;
         invert = TRUE;
         allow_multi_folds = FALSE;
-        RExC_naughty++;
+        MARK_NAUGHTY(1);
         if (skip_white) {
             RExC_parse = regpatws(pRExC_state, RExC_parse,
                                   FALSE /* means don't recognize comments */ );
@@ -13440,7 +13859,6 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state, I32 *flagp, U32 depth,
     if (UCHARAT(RExC_parse) == ']')
        goto charclassloop;
 
-parseit:
     while (1) {
         if  (RExC_parse >= stop_ptr) {
             break;
@@ -13480,8 +13898,14 @@ parseit:
         {
             namedclass = regpposixcc(pRExC_state, value, strict);
         }
-        else if (value == '\\') {
-           if (UTF) {
+        else if (value != '\\') {
+#ifdef EBCDIC
+            literal_endpoint++;
+#endif
+        }
+        else {
+            /* Is a backslash; get the code point of the char after it */
+           if (UTF && ! UTF8_IS_INVARIANT(UCHARAT(RExC_parse))) {
                value = utf8n_to_uvchr((U8*)RExC_parse,
                                   RExC_end - RExC_parse,
                                   &numlen, UTF8_ALLOW_DEFAULT);
@@ -13514,19 +13938,60 @@ parseit:
            case 'H':   namedclass = ANYOF_NHORIZWS;    break;
             case 'N':  /* Handle \N{NAME} in class */
                 {
-                    /* We only pay attention to the first char of
-                    multichar strings being returned. I kinda wonder
-                    if this makes sense as it does change the behaviour
-                    from earlier versions, OTOH that behaviour was broken
-                    as well. */
-                    if (! grok_bslash_N(pRExC_state, NULL, &value, flagp, depth,
-                                      TRUE, /* => charclass */
-                                      strict))
-                    {
-                        if (*flagp & RESTART_UTF8)
-                            FAIL("panic: grok_bslash_N set RESTART_UTF8");
-                        goto parseit;
+                    SV *as_text;
+                    STRLEN cp_count = grok_bslash_N(pRExC_state, NULL, &value,
+                                                    flagp, depth, &as_text);
+                    if (*flagp & RESTART_UTF8)
+                        FAIL("panic: grok_bslash_N set RESTART_UTF8");
+                    if (cp_count != 1) {    /* The typical case drops through */
+                        assert(cp_count != (STRLEN) -1);
+                        if (cp_count == 0) {
+                            if (strict) {
+                                RExC_parse++;   /* Position after the "}" */
+                                vFAIL("Zero length \\N{}");
+                            }
+                            else if (PASS2) {
+                                ckWARNreg(RExC_parse,
+                                        "Ignoring zero length \\N{} in character class");
+                            }
+                        }
+                        else { /* cp_count > 1 */
+                            if (! RExC_in_multi_char_class) {
+                                if (invert || range || *RExC_parse == '-') {
+                                    if (strict) {
+                                        RExC_parse--;
+                                        vFAIL("\\N{} in inverted character class or as a range end-point is restricted to one character");
+                                    }
+                                    else if (PASS2) {
+                                        ckWARNreg(RExC_parse, "Using just the first character returned by \\N{} in character class");
+                                    }
+                                }
+                                else {
+                                    multi_char_matches
+                                        = add_multi_match(multi_char_matches,
+                                                          as_text,
+                                                          cp_count);
+                                }
+                                break; /* <value> contains the first code
+                                          point. Drop out of the switch to
+                                          process it */
+                            }
+                        } /* End of cp_count != 1 */
+
+                        /* This element should not be processed further in this
+                         * class */
+                        element_count--;
+                        value = save_value;
+                        prevvalue = save_prevvalue;
+                        continue;   /* Back to top of loop to get next char */
                     }
+                    /* Here, is a single code point, and <value> contains it */
+#ifdef EBCDIC
+                    /* We consider named characters to be literal characters,
+                     * and they are Unicode */
+                    literal_endpoint++;
+                    unicode_range = TRUE;
+#endif
                 }
                 break;
            case 'p':
@@ -13649,7 +14114,8 @@ parseit:
                          * inappropriately, except that any \p{}, including
                          * this one forces Unicode semantics, which means there
                          * is no <depends_list> */
-                        ANYOF_FLAGS(ret) |= ANYOF_NONBITMAP_NON_UTF8;
+                        ANYOF_FLAGS(ret)
+                                      |= ANYOF_HAS_NONBITMAP_NON_UTF8_MATCHES;
                     }
                     else {
 
@@ -13705,7 +14171,7 @@ parseit:
            case 't':   value = '\t';                   break;
            case 'f':   value = '\f';                   break;
            case 'b':   value = '\b';                   break;
-           case 'e':   value = ASCII_TO_NATIVE('\033');break;
+           case 'e':   value = ESC_NATIVE;             break;
            case 'a':   value = '\a';                   break;
            case 'o':
                RExC_parse--;   /* function expects to be pointed at the 'o' */
@@ -13714,8 +14180,8 @@ parseit:
                    bool valid = grok_bslash_o(&RExC_parse,
                                               &value,
                                               &error_msg,
-                                               SIZE_ONLY,   /* warnings in pass
-                                                               1 only */
+                                               PASS2,   /* warnings only in
+                                                           pass 2 */
                                                strict,
                                                silence_non_portable,
                                                UTF);
@@ -13723,7 +14189,7 @@ parseit:
                        vFAIL(error_msg);
                    }
                }
-               if (PL_encoding && value < 0x100) {
+               if (IN_ENCODING && value < 0x100) {
                    goto recode_encoding;
                }
                break;
@@ -13734,7 +14200,7 @@ parseit:
                    bool valid = grok_bslash_x(&RExC_parse,
                                               &value,
                                               &error_msg,
-                                              TRUE, /* Output warnings */
+                                              PASS2, /* Output warnings */
                                                strict,
                                                silence_non_portable,
                                                UTF);
@@ -13742,11 +14208,11 @@ parseit:
                        vFAIL(error_msg);
                    }
                }
-               if (PL_encoding && value < 0x100)
+               if (IN_ENCODING && value < 0x100)
                    goto recode_encoding;
                break;
            case 'c':
-               value = grok_bslash_c(*RExC_parse++, SIZE_ONLY);
+               value = grok_bslash_c(*RExC_parse++, PASS2);
                break;
            case '0': case '1': case '2': case '3': case '4':
            case '5': case '6': case '7':
@@ -13774,19 +14240,19 @@ parseit:
                             (void)ReREFCNT_inc(RExC_rx_sv);
                         }
                     }
-                   if (PL_encoding && value < 0x100)
+                   if (IN_ENCODING && value < 0x100)
                        goto recode_encoding;
                    break;
                }
            recode_encoding:
                if (! RExC_override_recoding) {
-                   SV* enc = PL_encoding;
+                   SV* enc = _get_encoding();
                    value = reg_recode((const char)(U8)value, &enc);
                    if (!enc) {
                         if (strict) {
                             vFAIL("Invalid escape in the specified encoding");
                         }
-                        else if (SIZE_ONLY) {
+                        else if (PASS2) {
                             ckWARNreg(RExC_parse,
                                  "Invalid escape in the specified encoding");
                         }
@@ -13811,10 +14277,6 @@ parseit:
                break;
            }   /* End of switch on char following backslash */
        } /* end of handling backslash escape sequences */
-#ifdef EBCDIC
-        else
-            literal_endpoint++;
-#endif
 
         /* Here, we have the current token in 'value' */
 
@@ -13872,18 +14334,18 @@ parseit:
                     else {
                         RExC_emit += ANYOF_POSIXL_SKIP - ANYOF_SKIP;
                     }
-                    ANYOF_FLAGS(ret) |= ANYOF_POSIXL;
+                    ANYOF_FLAGS(ret) |= ANYOF_MATCHES_POSIXL;
                     ANYOF_POSIXL_ZERO(ret);
                 }
 
                 /* Coverity thinks it is possible for this to be negative; both
                  * jhi and khw think it's not, but be safer */
-                assert(! (ANYOF_FLAGS(ret) & ANYOF_POSIXL)
+                assert(! (ANYOF_FLAGS(ret) & ANYOF_MATCHES_POSIXL)
                        || (namedclass + ((namedclass % 2) ? -1 : 1)) >= 0);
 
                 /* See if it already matches the complement of this POSIX
                  * class */
-                if ((ANYOF_FLAGS(ret) & ANYOF_POSIXL)
+                if ((ANYOF_FLAGS(ret) & ANYOF_MATCHES_POSIXL)
                     && ANYOF_POSIXL_TEST(ret, namedclass + ((namedclass % 2)
                                                             ? -1
                                                             : 1)))
@@ -13968,25 +14430,41 @@ parseit:
                                                      namedclass % 2 != 0,
                                                      posixes_ptr);
                 }
-                continue;   /* Go get next character */
            }
        } /* end of namedclass \blah */
 
-        /* Here, we have a single value.  If 'range' is set, it is the ending
-         * of a range--check its validity.  Later, we will handle each
-         * individual code point in the range.  If 'range' isn't set, this
-         * could be the beginning of a range, so check for that by looking
-         * ahead to see if the next real character to be processed is the range
-         * indicator--the minus sign */
-
         if (skip_white) {
             RExC_parse = regpatws(pRExC_state, RExC_parse,
                                 FALSE /* means don't recognize comments */ );
         }
 
+        /* If 'range' is set, 'value' is the ending of a range--check its
+         * validity.  (If value isn't a single code point in the case of a
+         * range, we should have figured that out above in the code that
+         * catches false ranges).  Later, we will handle each individual code
+         * point in the range.  If 'range' isn't set, this could be the
+         * beginning of a range, so check for that by looking ahead to see if
+         * the next real character to be processed is the range indicator--the
+         * minus sign */
+
        if (range) {
+#ifdef EBCDIC
+            /* For unicode ranges, we have to test that the Unicode as opposed
+             * to the native values are not decreasing.  (Above 255, and there
+             * is no difference between native and Unicode) */
+           if (unicode_range && prevvalue < 255 && value < 255) {
+                if (NATIVE_TO_LATIN1(prevvalue) > NATIVE_TO_LATIN1(value)) {
+                    goto backwards_range;
+                }
+            }
+            else
+#endif
            if (prevvalue > value) /* b-a */ {
-               const int w = RExC_parse - rangebegin;
+               int w;
+#ifdef EBCDIC
+              backwards_range:
+#endif
+                w = RExC_parse - rangebegin;
                 vFAIL2utf8f(
                     "Invalid [] range \"%"UTF8f"\"",
                     UTF8fARG(UTF, w, rangebegin));
@@ -14013,15 +14491,15 @@ parseit:
 
                     /* a bad range like \w-, [:word:]- ? */
                     if (namedclass > OOB_NAMEDCLASS) {
-                        if (strict || ckWARN(WARN_REGEXP)) {
-                            const int w =
-                                RExC_parse >= rangebegin ?
-                                RExC_parse - rangebegin : 0;
+                        if (strict || (PASS2 && ckWARN(WARN_REGEXP))) {
+                            const int w = RExC_parse >= rangebegin
+                                          ?  RExC_parse - rangebegin
+                                          : 0;
                             if (strict) {
                                 vFAIL4("False [] range \"%*.*s\"",
                                     w, w, rangebegin);
                             }
-                            else {
+                            else if (PASS2) {
                                 vWARN4(RExC_parse,
                                     "False [] range \"%*.*s\"",
                                     w, w, rangebegin);
@@ -14038,8 +14516,13 @@ parseit:
            }
        }
 
-        /* Here, <prevvalue> is the beginning of the range, if any; or <value>
-         * if not */
+        if (namedclass > OOB_NAMEDCLASS) {
+            continue;
+        }
+
+        /* Here, we have a single value this time through the loop, and
+         * <prevvalue> is the beginning of the range, if any; or <value> if
+         * not. */
 
        /* non-Latin1 code point implies unicode semantics.  Must be set in
         * pass1 so is there for the whole of pass 2 */
@@ -14087,44 +14570,17 @@ parseit:
                      * again.  Otherwise add this character to the list of
                      * multi-char folds. */
                     if (! RExC_in_multi_char_class) {
-                        AV** this_array_ptr;
-                        AV* this_array;
                         STRLEN cp_count = utf8_length(foldbuf,
                                                       foldbuf + foldlen);
                         SV* multi_fold = sv_2mortal(newSVpvs(""));
 
                         Perl_sv_catpvf(aTHX_ multi_fold, "\\x{%"UVXf"}", value);
 
+                        multi_char_matches
+                                        = add_multi_match(multi_char_matches,
+                                                          multi_fold,
+                                                          cp_count);
 
-                        if (! multi_char_matches) {
-                            multi_char_matches = newAV();
-                        }
-
-                        /* <multi_char_matches> is actually an array of arrays.
-                         * There will be one or two top-level elements: [2],
-                         * and/or [3].  The [2] element is an array, each
-                         * element thereof is a character which folds to TWO
-                         * characters; [3] is for folds to THREE characters.
-                         * (Unicode guarantees a maximum of 3 characters in any
-                         * fold.)  When we rewrite the character class below,
-                         * we will do so such that the longest folds are
-                         * written first, so that it prefers the longest
-                         * matching strings first.  This is done even if it
-                         * turns out that any quantifier is non-greedy, out of
-                         * programmer laziness.  Tom Christiansen has agreed
-                         * that this is ok.  This makes the test for the
-                         * ligature 'ffi' come before the test for 'ff' */
-                        if (av_exists(multi_char_matches, cp_count)) {
-                            this_array_ptr = (AV**) av_fetch(multi_char_matches,
-                                                             cp_count, FALSE);
-                            this_array = *this_array_ptr;
-                        }
-                        else {
-                            this_array = newAV();
-                            av_store(multi_char_matches, cp_count,
-                                     (SV*) this_array);
-                        }
-                        av_push(this_array, multi_fold);
                     }
 
                     /* This element should not be processed further in this
@@ -14143,31 +14599,40 @@ parseit:
             cp_foldable_list = _add_range_to_invlist(cp_foldable_list,
                                                      prevvalue, value);
 #else
-            SV* this_range = _new_invlist(1);
-            _append_range_to_invlist(this_range, prevvalue, value);
-
-            /* In EBCDIC, the ranges 'A-Z' and 'a-z' are each not contiguous.
-             * If this range was specified using something like 'i-j', we want
-             * to include only the 'i' and the 'j', and not anything in
-             * between, so exclude non-ASCII, non-alphabetics from it.
-             * However, if the range was specified with something like
-             * [\x89-\x91] or [\x89-j], all code points within it should be
-             * included.  literal_endpoint==2 means both ends of the range used
-             * a literal character, not \x{foo} */
-           if (literal_endpoint == 2
-                && ((prevvalue >= 'a' && value <= 'z')
-                    || (prevvalue >= 'A' && value <= 'Z')))
+            /* On non-ASCII platforms, for ranges that span all of 0..255, and
+             * ones that don't require special handling, we can just add the
+             * range like we do for ASCII platforms */
+            if ((UNLIKELY(prevvalue == 0) && value >= 255)
+                || ! (prevvalue < 256
+                      && (unicode_range
+                          || (literal_endpoint == 2
+                              && ((isLOWER_A(prevvalue) && isLOWER_A(value))
+                                  || (isUPPER_A(prevvalue)
+                                      && isUPPER_A(value)))))))
             {
-                _invlist_intersection(this_range, PL_XPosix_ptrs[_CC_ASCII],
-                                      &this_range);
-
-                /* Since this above only contains ascii, the intersection of it
-                 * with anything will still yield only ascii */
-                _invlist_intersection(this_range, PL_XPosix_ptrs[_CC_ALPHA],
-                                      &this_range);
+                cp_foldable_list = _add_range_to_invlist(cp_foldable_list,
+                                                         prevvalue, value);
+            }
+            else {
+                /* Here, requires special handling.  This can be because it is
+                 * a range whose code points are considered to be Unicode, and
+                 * so must be individually translated into native, or because
+                 * its a subrange of 'A-Z' or 'a-z' which each aren't
+                 * contiguous in EBCDIC, but we have defined them to include
+                 * only the "expected" upper or lower case ASCII alphabetics.
+                 * Subranges above 255 are the same in native and Unicode, so
+                 * can be added as a range */
+                U8 start = NATIVE_TO_LATIN1(prevvalue);
+                unsigned j;
+                U8 end = (value < 256) ? NATIVE_TO_LATIN1(value) : 255;
+                for (j = start; j <= end; j++) {
+                    cp_foldable_list = add_cp_to_invlist(cp_foldable_list, LATIN1_TO_NATIVE(j));
+                }
+                if (value > 255) {
+                    cp_foldable_list = _add_range_to_invlist(cp_foldable_list,
+                                                             256, value);
+                }
             }
-            _invlist_union(cp_foldable_list, this_range, &cp_foldable_list);
-            literal_endpoint = 0;
 #endif
         }
 
@@ -14238,6 +14703,7 @@ parseit:
        RExC_parse = SvPV(substitute_parse, len);
        RExC_end = RExC_parse + len;
         RExC_in_multi_char_class = 1;
+       RExC_override_recoding = 1;
         RExC_emit = (regnode *)orig_emit;
 
        ret = reg(pRExC_state, 1, &reg_flags, depth+1);
@@ -14247,6 +14713,7 @@ parseit:
        RExC_parse = save_parse;
        RExC_end = save_end;
        RExC_in_multi_char_class = 0;
+       RExC_override_recoding = 0;
         SvREFCNT_dec_NN(multi_char_matches);
         return ret;
     }
@@ -14349,7 +14816,7 @@ parseit:
                 if (! LOC && value == '\n') {
                     op = REG_ANY; /* Optimize [^\n] */
                     *flagp |= HASWIDTH|SIMPLE;
-                    RExC_naughty++;
+                    MARK_NAUGHTY(1);
                 }
             }
             else if (value < 256 || UTF) {
@@ -14605,7 +15072,7 @@ parseit:
             if (DEPENDS_SEMANTICS) {
                 /* Under /d, everything in the upper half of the Latin1 range
                  * matches these complements */
-                ANYOF_FLAGS(ret) |= ANYOF_NON_UTF8_NON_ASCII_ALL;
+                ANYOF_FLAGS(ret) |= ANYOF_MATCHES_ALL_NON_UTF8_NON_ASCII;
             }
             else if (AT_LEAST_ASCII_RESTRICTED) {
                 /* Under /a and /aa, everything above ASCII matches these
@@ -14856,7 +15323,7 @@ parseit:
             if (end == UV_MAX) {
                 op = SANY;
                 *flagp |= HASWIDTH|SIMPLE;
-                RExC_naughty++;
+                MARK_NAUGHTY(1);
             }
             else if (end == '\n' - 1
                     && invlist_iternext(cp_list, &start, &end)
@@ -14864,7 +15331,7 @@ parseit:
             {
                 op = REG_ANY;
                 *flagp |= HASWIDTH|SIMPLE;
-                RExC_naughty++;
+                MARK_NAUGHTY(1);
             }
         }
         invlist_iterfinish(cp_list);
@@ -14911,7 +15378,7 @@ parseit:
        else {
            cp_list = depends_list;
        }
-        ANYOF_FLAGS(ret) |= ANYOF_UTF8;
+        ANYOF_FLAGS(ret) |= ANYOF_HAS_UTF8_NONBITMAP_MATCHES;
     }
 
     /* If there is a swash and more than one element, we can't use the swash in
@@ -14921,6 +15388,10 @@ parseit:
        swash = NULL;
     }
 
+    /* Note that the optimization of using 'swash' if it is the only thing in
+     * the class doesn't have us change swash at all, so it can include things
+     * that are also in the bitmap; otherwise we have purposely deleted that
+     * duplicate information */
     set_ANYOF_arg(pRExC_state, ret, cp_list,
                   (HAS_NONLOCALE_RUNTIME_PROPERTY_DEFINITION)
                    ? listsv : NULL,
@@ -14949,7 +15420,7 @@ S_set_ANYOF_arg(pTHX_ RExC_state_t* const pRExC_state,
 {
     /* Sets the arg field of an ANYOF-type node 'node', using information about
      * the node passed-in.  If there is nothing outside the node's bitmap, the
-     * arg is set to ANYOF_NONBITMAP_EMPTY.  Otherwise, it sets the argument to
+     * arg is set to ANYOF_ONLY_HAS_BITMAP.  Otherwise, it sets the argument to
      * the count returned by add_data(), having allocated and stored an array,
      * av, that that count references, as follows:
      *  av[0] stores the character class description in its textual form.
@@ -14975,15 +15446,17 @@ S_set_ANYOF_arg(pTHX_ RExC_state_t* const pRExC_state,
 
     if (! cp_list && ! runtime_defns && ! only_utf8_locale_list) {
         assert(! (ANYOF_FLAGS(node)
-                    & (ANYOF_UTF8|ANYOF_NONBITMAP_NON_UTF8)));
-       ARG_SET(node, ANYOF_NONBITMAP_EMPTY);
+                  & (ANYOF_HAS_UTF8_NONBITMAP_MATCHES
+                     |ANYOF_HAS_NONBITMAP_NON_UTF8_MATCHES)));
+       ARG_SET(node, ANYOF_ONLY_HAS_BITMAP);
     }
     else {
        AV * const av = newAV();
        SV *rv;
 
         assert(ANYOF_FLAGS(node)
-                    & (ANYOF_UTF8|ANYOF_NONBITMAP_NON_UTF8|ANYOF_LOC_FOLD));
+               & (ANYOF_HAS_UTF8_NONBITMAP_MATCHES
+                  |ANYOF_HAS_NONBITMAP_NON_UTF8_MATCHES|ANYOF_LOC_FOLD));
 
        av_store(av, 0, (runtime_defns)
                        ? SvREFCNT_inc(runtime_defns) : &PL_sv_undef);
@@ -15014,6 +15487,135 @@ S_set_ANYOF_arg(pTHX_ RExC_state_t* const pRExC_state,
     }
 }
 
+#if !defined(PERL_IN_XSUB_RE) || defined(PLUGGABLE_RE_EXTENSION)
+SV *
+Perl__get_regclass_nonbitmap_data(pTHX_ const regexp *prog,
+                                        const regnode* node,
+                                        bool doinit,
+                                        SV** listsvp,
+                                        SV** only_utf8_locale_ptr,
+                                        SV*  exclude_list)
+
+{
+    /* For internal core use only.
+     * Returns the swash for the input 'node' in the regex 'prog'.
+     * If <doinit> is 'true', will attempt to create the swash if not already
+     *   done.
+     * If <listsvp> is non-null, will return the printable contents of the
+     *    swash.  This can be used to get debugging information even before the
+     *    swash exists, by calling this function with 'doinit' set to false, in
+     *    which case the components that will be used to eventually create the
+     *    swash are returned  (in a printable form).
+     * If <exclude_list> is not NULL, it is an inversion list of things to
+     *    exclude from what's returned in <listsvp>.
+     * Tied intimately to how S_set_ANYOF_arg sets up the data structure.  Note
+     * that, in spite of this function's name, the swash it returns may include
+     * the bitmap data as well */
+
+    SV *sw  = NULL;
+    SV *si  = NULL;         /* Input swash initialization string */
+    SV*  invlist = NULL;
+
+    RXi_GET_DECL(prog,progi);
+    const struct reg_data * const data = prog ? progi->data : NULL;
+
+    PERL_ARGS_ASSERT__GET_REGCLASS_NONBITMAP_DATA;
+
+    assert(ANYOF_FLAGS(node)
+        & (ANYOF_HAS_UTF8_NONBITMAP_MATCHES
+           |ANYOF_HAS_NONBITMAP_NON_UTF8_MATCHES|ANYOF_LOC_FOLD));
+
+    if (data && data->count) {
+       const U32 n = ARG(node);
+
+       if (data->what[n] == 's') {
+           SV * const rv = MUTABLE_SV(data->data[n]);
+           AV * const av = MUTABLE_AV(SvRV(rv));
+           SV **const ary = AvARRAY(av);
+           U8 swash_init_flags = _CORE_SWASH_INIT_ACCEPT_INVLIST;
+
+           si = *ary;  /* ary[0] = the string to initialize the swash with */
+
+           /* Elements 3 and 4 are either both present or both absent. [3] is
+            * any inversion list generated at compile time; [4] indicates if
+            * that inversion list has any user-defined properties in it. */
+            if (av_tindex(av) >= 2) {
+                if (only_utf8_locale_ptr
+                    && ary[2]
+                    && ary[2] != &PL_sv_undef)
+                {
+                    *only_utf8_locale_ptr = ary[2];
+                }
+                else {
+                    assert(only_utf8_locale_ptr);
+                    *only_utf8_locale_ptr = NULL;
+                }
+
+                if (av_tindex(av) >= 3) {
+                    invlist = ary[3];
+                    if (SvUV(ary[4])) {
+                        swash_init_flags |= _CORE_SWASH_INIT_USER_DEFINED_PROPERTY;
+                    }
+                }
+                else {
+                    invlist = NULL;
+                }
+           }
+
+           /* Element [1] is reserved for the set-up swash.  If already there,
+            * return it; if not, create it and store it there */
+           if (ary[1] && SvROK(ary[1])) {
+               sw = ary[1];
+           }
+           else if (doinit && ((si && si != &PL_sv_undef)
+                                 || (invlist && invlist != &PL_sv_undef))) {
+               assert(si);
+               sw = _core_swash_init("utf8", /* the utf8 package */
+                                     "", /* nameless */
+                                     si,
+                                     1, /* binary */
+                                     0, /* not from tr/// */
+                                     invlist,
+                                     &swash_init_flags);
+               (void)av_store(av, 1, sw);
+           }
+       }
+    }
+
+    /* If requested, return a printable version of what this swash matches */
+    if (listsvp) {
+       SV* matches_string = newSVpvs("");
+
+        /* The swash should be used, if possible, to get the data, as it
+         * contains the resolved data.  But this function can be called at
+         * compile-time, before everything gets resolved, in which case we
+         * return the currently best available information, which is the string
+         * that will eventually be used to do that resolving, 'si' */
+       if ((! sw || (invlist = _get_swash_invlist(sw)) == NULL)
+            && (si && si != &PL_sv_undef))
+        {
+           sv_catsv(matches_string, si);
+       }
+
+       /* Add the inversion list to whatever we have.  This may have come from
+        * the swash, or from an input parameter */
+       if (invlist) {
+            if (exclude_list) {
+                SV* clone = invlist_clone(invlist);
+                _invlist_subtract(clone, exclude_list, &clone);
+                sv_catsv(matches_string, _invlist_contents(clone));
+                SvREFCNT_dec_NN(clone);
+            }
+            else {
+                sv_catsv(matches_string, _invlist_contents(invlist));
+            }
+       }
+       *listsvp = matches_string;
+    }
+
+    return sw;
+}
+#endif /* !defined(PERL_IN_XSUB_RE) || defined(PLUGGABLE_RE_EXTENSION) */
 
 /* reg_skipcomment()
 
@@ -15093,21 +15695,23 @@ S_nextchar(pTHX_ RExC_state_t *pRExC_state)
     }
 }
 
-/*
-- reg_node - emit a node
-*/
-STATIC regnode *                       /* Location. */
-S_reg_node(pTHX_ RExC_state_t *pRExC_state, U8 op)
+STATIC regnode *
+S_regnode_guts(pTHX_ RExC_state_t *pRExC_state, const U8 op, const STRLEN extra_size, const char* const name)
 {
-    regnode *ptr;
+    /* Allocate a regnode for 'op' and returns it, with 'extra_size' extra
+     * space.  In pass1, it aligns and increments RExC_size; in pass2,
+     * RExC_emit */
+
     regnode * const ret = RExC_emit;
     GET_RE_DEBUG_FLAGS_DECL;
 
-    PERL_ARGS_ASSERT_REG_NODE;
+    PERL_ARGS_ASSERT_REGNODE_GUTS;
+
+    assert(extra_size >= regarglen[op]);
 
     if (SIZE_ONLY) {
        SIZE_ALIGN(RExC_size);
-       RExC_size += 1;
+       RExC_size += 1 + extra_size;
        return(ret);
     }
     if (RExC_emit >= RExC_emit_bound)
@@ -15115,13 +15719,13 @@ S_reg_node(pTHX_ RExC_state_t *pRExC_state, U8 op)
                   op, (void*)RExC_emit, (void*)RExC_emit_bound);
 
     NODE_ALIGN_FILL(ret);
-    ptr = ret;
-    FILL_ADVANCE_NODE(ptr, op);
-#ifdef RE_TRACK_PATTERN_OFFSETS
+#ifndef RE_TRACK_PATTERN_OFFSETS
+    PERL_UNUSED_ARG(name);
+#else
     if (RExC_offsets) {         /* MJD */
        MJD_OFFSET_DEBUG(
               ("%s:%d: (op %s) %s %"UVuf" (len %"UVuf") (max %"UVuf").\n",
-              "reg_node", __LINE__,
+              name, __LINE__,
               PL_reg_name[op],
               (UV)(RExC_emit - RExC_emit_start) > RExC_offsets[0]
                ? "Overwriting end of array!\n" : "OK",
@@ -15131,7 +15735,26 @@ S_reg_node(pTHX_ RExC_state_t *pRExC_state, U8 op)
        Set_Node_Offset(RExC_emit, RExC_parse + (op == END));
     }
 #endif
-    RExC_emit = ptr;
+    return(ret);
+}
+
+/*
+- reg_node - emit a node
+*/
+STATIC regnode *                       /* Location. */
+S_reg_node(pTHX_ RExC_state_t *pRExC_state, U8 op)
+{
+    regnode * const ret = regnode_guts(pRExC_state, op, regarglen[op], "reg_node");
+
+    PERL_ARGS_ASSERT_REG_NODE;
+
+    assert(regarglen[op] == 0);
+
+    if (PASS2) {
+        regnode *ptr = ret;
+        FILL_ADVANCE_NODE(ptr, op);
+        RExC_emit = ptr;
+    }
     return(ret);
 }
 
@@ -15141,54 +15764,36 @@ S_reg_node(pTHX_ RExC_state_t *pRExC_state, U8 op)
 STATIC regnode *                       /* Location. */
 S_reganode(pTHX_ RExC_state_t *pRExC_state, U8 op, U32 arg)
 {
-    regnode *ptr;
-    regnode * const ret = RExC_emit;
-    GET_RE_DEBUG_FLAGS_DECL;
+    regnode * const ret = regnode_guts(pRExC_state, op, regarglen[op], "reganode");
 
     PERL_ARGS_ASSERT_REGANODE;
 
-    if (SIZE_ONLY) {
-       SIZE_ALIGN(RExC_size);
-       RExC_size += 2;
-       /*
-          We can't do this:
+    assert(regarglen[op] == 1);
 
-          assert(2==regarglen[op]+1);
+    if (PASS2) {
+        regnode *ptr = ret;
+        FILL_ADVANCE_NODE_ARG(ptr, op, arg);
+        RExC_emit = ptr;
+    }
+    return(ret);
+}
 
-          Anything larger than this has to allocate the extra amount.
-          If we changed this to be:
+STATIC regnode *
+S_reg2Lanode(pTHX_ RExC_state_t *pRExC_state, const U8 op, const U32 arg1, const I32 arg2)
+{
+    /* emit a node with U32 and I32 arguments */
 
-          RExC_size += (1 + regarglen[op]);
+    regnode * const ret = regnode_guts(pRExC_state, op, regarglen[op], "reg2Lanode");
 
-          then it wouldn't matter. Its not clear what side effect
-          might come from that so its not done so far.
-          -- dmq
-       */
-       return(ret);
-    }
-    if (RExC_emit >= RExC_emit_bound)
-        Perl_croak(aTHX_ "panic: reg_node overrun trying to emit %d, %p>=%p",
-                  op, (void*)RExC_emit, (void*)RExC_emit_bound);
+    PERL_ARGS_ASSERT_REG2LANODE;
 
-    NODE_ALIGN_FILL(ret);
-    ptr = ret;
-    FILL_ADVANCE_NODE_ARG(ptr, op, arg);
-#ifdef RE_TRACK_PATTERN_OFFSETS
-    if (RExC_offsets) {         /* MJD */
-       MJD_OFFSET_DEBUG(
-              ("%s(%d): (op %s) %s %"UVuf" <- %"UVuf" (max %"UVuf").\n",
-              "reganode",
-             __LINE__,
-             PL_reg_name[op],
-              (UV)(RExC_emit - RExC_emit_start) > RExC_offsets[0] ?
-              "Overwriting end of array!\n" : "OK",
-              (UV)(RExC_emit - RExC_emit_start),
-              (UV)(RExC_parse - RExC_start),
-              (UV)RExC_offsets[0]));
-       Set_Cur_Node_Offset;
+    assert(regarglen[op] == 2);
+
+    if (PASS2) {
+        regnode *ptr = ret;
+        FILL_ADVANCE_NODE_2L_ARG(ptr, op, arg1, arg2);
+        RExC_emit = ptr;
     }
-#endif
-    RExC_emit = ptr;
     return(ret);
 }
 
@@ -15318,11 +15923,10 @@ S_regtail(pTHX_ RExC_state_t *pRExC_state, regnode *p,
     for (;;) {
        regnode * const temp = regnext(scan);
         DEBUG_PARSE_r({
-            SV * const mysv=sv_newmortal();
             DEBUG_PARSE_MSG((scan==p ? "tail" : ""));
-            regprop(RExC_rx, mysv, scan, NULL);
+            regprop(RExC_rx, RExC_mysv, scan, NULL, pRExC_state);
             PerlIO_printf(Perl_debug_log, "~ %s (%d) %s %s\n",
-                SvPV_nolen_const(mysv), REG_NODE_NUM(scan),
+                SvPV_nolen_const(RExC_mysv), REG_NODE_NUM(scan),
                     (temp == NULL ? "->" : ""),
                     (temp == NULL ? PL_reg_name[OP(val)] : "")
             );
@@ -15407,11 +16011,10 @@ S_regtail_study(pTHX_ RExC_state_t *pRExC_state, regnode *p,
             }
         }
         DEBUG_PARSE_r({
-            SV * const mysv=sv_newmortal();
             DEBUG_PARSE_MSG((scan==p ? "tsdy" : ""));
-            regprop(RExC_rx, mysv, scan, NULL);
+            regprop(RExC_rx, RExC_mysv, scan, NULL, pRExC_state);
             PerlIO_printf(Perl_debug_log, "~ %s (%d) -> %s\n",
-                SvPV_nolen_const(mysv),
+                SvPV_nolen_const(RExC_mysv),
                 REG_NODE_NUM(scan),
                 PL_reg_name[exact]);
         });
@@ -15420,12 +16023,11 @@ S_regtail_study(pTHX_ RExC_state_t *pRExC_state, regnode *p,
        scan = temp;
     }
     DEBUG_PARSE_r({
-        SV * const mysv_val=sv_newmortal();
         DEBUG_PARSE_MSG("");
-        regprop(RExC_rx, mysv_val, val, NULL);
+        regprop(RExC_rx, RExC_mysv, val, NULL, pRExC_state);
         PerlIO_printf(Perl_debug_log,
                       "~ attach to %s (%"IVdf") offset to %"IVdf"\n",
-                     SvPV_nolen_const(mysv_val),
+                     SvPV_nolen_const(RExC_mysv),
                      (IV)REG_NODE_NUM(val),
                      (IV)(val - scan)
         );
@@ -15577,13 +16179,11 @@ Perl_regdump(pTHX_ const regexp *r)
        PerlIO_printf(Perl_debug_log, ") ");
 
     if (ri->regstclass) {
-       regprop(r, sv, ri->regstclass, NULL);
+        regprop(r, sv, ri->regstclass, NULL, NULL);
        PerlIO_printf(Perl_debug_log, "stclass %s ", SvPVX_const(sv));
     }
     if (r->intflags & PREGf_ANCH) {
        PerlIO_printf(Perl_debug_log, "anchored");
-        if (r->intflags & PREGf_ANCH_BOL)
-           PerlIO_printf(Perl_debug_log, "(BOL)");
         if (r->intflags & PREGf_ANCH_MBOL)
            PerlIO_printf(Perl_debug_log, "(MBOL)");
         if (r->intflags & PREGf_ANCH_SBOL)
@@ -15618,7 +16218,7 @@ Perl_regdump(pTHX_ const regexp *r)
 */
 
 void
-Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_info *reginfo)
+Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_info *reginfo, const RExC_state_t *pRExC_state)
 {
 #ifdef DEBUGGING
     int k;
@@ -15673,7 +16273,7 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
 
     PERL_ARGS_ASSERT_REGPROP;
 
-    sv_setpvs(sv, "");
+    sv_setpvn(sv, "", 0);
 
     if (OP(o) > REGNODE_MAX)           /* regnode.type is unsigned */
        /* It would be nice to FAIL() here, but this may be called from
@@ -15723,9 +16323,11 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
         );
         if ( IS_ANYOF_TRIE(op) || trie->bitmap ) {
             sv_catpvs(sv, "[");
-            (void) put_latin1_charclass_innards(sv, IS_ANYOF_TRIE(op)
-                                                   ? ANYOF_BITMAP(o)
-                                                   : TRIE_BITMAP(trie));
+            (void) put_charclass_bitmap_innards(sv,
+                                                (IS_ANYOF_TRIE(op))
+                                                 ? ANYOF_BITMAP(o)
+                                                 : TRIE_BITMAP(trie),
+                                                NULL);
             sv_catpvs(sv, "]");
         }
 
@@ -15739,19 +16341,23 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
     else if (k == REF || k == OPEN || k == CLOSE
              || k == GROUPP || OP(o)==ACCEPT)
     {
+        AV *name_list= NULL;
        Perl_sv_catpvf(aTHX_ sv, "%d", (int)ARG(o));    /* Parenth number */
        if ( RXp_PAREN_NAMES(prog) ) {
+            name_list= MUTABLE_AV(progi->data->data[progi->name_list_idx]);
+        } else if ( pRExC_state ) {
+            name_list= RExC_paren_name_list;
+        }
+        if (name_list) {
             if ( k != REF || (OP(o) < NREF)) {
-               AV *list= MUTABLE_AV(progi->data->data[progi->name_list_idx]);
-               SV **name= av_fetch(list, ARG(o), 0 );
+                SV **name= av_fetch(name_list, ARG(o), 0 );
                if (name)
                    Perl_sv_catpvf(aTHX_ sv, " '%"SVf"'", SVfARG(*name));
             }
             else {
-                AV *list= MUTABLE_AV(progi->data->data[ progi->name_list_idx ]);
                 SV *sv_dat= MUTABLE_SV(progi->data->data[ ARG( o ) ]);
                 I32 *nums=(I32*)SvPVX(sv_dat);
-                SV **name= av_fetch(list, nums[0], 0 );
+                SV **name= av_fetch(name_list, nums[0], 0 );
                 I32 n;
                 if (name) {
                     for ( n=0; n<SvIVX(sv_dat); n++ ) {
@@ -15776,9 +16382,22 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
                     PERL_PV_ESCAPE_UNI_DETECT|PERL_PV_PRETTY_NOCLEAR|PERL_PV_PRETTY_ELLIPSES|PERL_PV_PRETTY_QUOTE );
             }
         }
-    } else if (k == GOSUB)
+    } else if (k == GOSUB) {
+        AV *name_list= NULL;
+        if ( RXp_PAREN_NAMES(prog) ) {
+            name_list= MUTABLE_AV(progi->data->data[progi->name_list_idx]);
+        } else if ( pRExC_state ) {
+            name_list= RExC_paren_name_list;
+        }
+
         /* Paren and offset */
        Perl_sv_catpvf(aTHX_ sv, "%d[%+d]", (int)ARG(o),(int)ARG2L(o));
+        if (name_list) {
+            SV **name= av_fetch(name_list, ARG(o), 0 );
+            if (name)
+                Perl_sv_catpvf(aTHX_ sv, " '%"SVf"'", SVfARG(*name));
+        }
+    }
     else if (k == VERB) {
         if (!o->flags)
             Perl_sv_catpvf(aTHX_ sv, ":%"SVf,
@@ -15789,6 +16408,7 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
     else if (k == ANYOF) {
        const U8 flags = ANYOF_FLAGS(o);
        int do_sep = 0;
+        SV* bitmap_invlist;  /* Will hold what the bit map contains */
 
 
        if (flags & ANYOF_LOCALE_FLAGS)
@@ -15799,8 +16419,10 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
        if (flags & ANYOF_INVERT)
            sv_catpvs(sv, "^");
 
-       /* output what the standard cp 0-255 bitmap matches */
-        do_sep = put_latin1_charclass_innards(sv, ANYOF_BITMAP(o));
+        /* output what the standard cp 0-NUM_ANYOF_CODE_POINTS-1 bitmap matches
+         * */
+        do_sep = put_charclass_bitmap_innards(sv, ANYOF_BITMAP(o),
+                                                            &bitmap_invlist);
 
         /* output any special charclass tests (used entirely under use
          * locale) * */
@@ -15814,9 +16436,9 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
             }
         }
 
-       if ((flags & (ANYOF_ABOVE_LATIN1_ALL
-                      |ANYOF_UTF8
-                      |ANYOF_NONBITMAP_NON_UTF8
+       if ((flags & (ANYOF_MATCHES_ALL_ABOVE_BITMAP
+                      |ANYOF_HAS_UTF8_NONBITMAP_MATCHES
+                      |ANYOF_HAS_NONBITMAP_NON_UTF8_MATCHES
                       |ANYOF_LOC_FOLD)))
         {
             if (do_sep) {
@@ -15826,22 +16448,25 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
                     sv_catpvs(sv, "^");
             }
 
-            if (flags & ANYOF_NON_UTF8_NON_ASCII_ALL) {
+            if (flags & ANYOF_MATCHES_ALL_NON_UTF8_NON_ASCII) {
                 sv_catpvs(sv, "{non-utf8-latin1-all}");
             }
 
             /* output information about the unicode matching */
-            if (flags & ANYOF_ABOVE_LATIN1_ALL)
-                sv_catpvs(sv, "{unicode_all}");
-            else if (ARG(o) != ANYOF_NONBITMAP_EMPTY) {
+            if (flags & ANYOF_MATCHES_ALL_ABOVE_BITMAP)
+                sv_catpvs(sv, "{above_bitmap_all}");
+            else if (ARG(o) != ANYOF_ONLY_HAS_BITMAP) {
                 SV *lv; /* Set if there is something outside the bit map. */
                 bool byte_output = FALSE;   /* If something in the bitmap has
                                                been output */
                 SV *only_utf8_locale;
 
-                /* Get the stuff that wasn't in the bitmap */
+                /* Get the stuff that wasn't in the bitmap.  'bitmap_invlist'
+                 * is used to guarantee that nothing in the bitmap gets
+                 * returned */
                 (void) _get_regclass_nonbitmap_data(prog, o, FALSE,
-                                                    &lv, &only_utf8_locale);
+                                                    &lv, &only_utf8_locale,
+                                                    bitmap_invlist);
                 if (lv && lv != &PL_sv_undef) {
                     char *s = savesvpv(lv);
                     char * const origs = s;
@@ -15852,7 +16477,7 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
                     if (*s == '\n') {
                         const char * const t = ++s;
 
-                        if (flags & ANYOF_NONBITMAP_NON_UTF8) {
+                        if (flags & ANYOF_HAS_NONBITMAP_NON_UTF8_MATCHES) {
                             sv_catpvs(sv, "{outside bitmap}");
                         }
                         else {
@@ -15904,7 +16529,7 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
                     invlist_iterinit(only_utf8_locale);
                     while (invlist_iternext(only_utf8_locale,
                                             &start, &end)) {
-                        put_range(sv, start, end);
+                        put_range(sv, start, end, FALSE);
                         max_entries --;
                         if (max_entries < 0) {
                             sv_catpvs(sv, "...");
@@ -15915,6 +16540,8 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
                 }
             }
        }
+        SvREFCNT_dec(bitmap_invlist);
+
 
        Perl_sv_catpvf(aTHX_ sv, "%s]", PL_colors[1]);
     }
@@ -15935,12 +16562,15 @@ Perl_regprop(pTHX_ const regexp *prog, SV *sv, const regnode *o, const regmatch_
     }
     else if (k == BRANCHJ && (OP(o) == UNLESSM || OP(o) == IFMATCH))
        Perl_sv_catpvf(aTHX_ sv, "[%d]", -(o->flags));
+    else if (OP(o) == SBOL)
+        Perl_sv_catpvf(aTHX_ sv, " /%s/", o->flags ? "\\A" : "^");
 #else
     PERL_UNUSED_CONTEXT;
     PERL_UNUSED_ARG(sv);
     PERL_UNUSED_ARG(o);
     PERL_UNUSED_ARG(prog);
     PERL_UNUSED_ARG(reginfo);
+    PERL_UNUSED_ARG(pRExC_state);
 #endif /* DEBUGGING */
 }
 
@@ -16507,202 +17137,297 @@ S_re_croak2(pTHX_ bool utf8, const char* pat1,const char* pat2,...)
     Perl_croak(aTHX_ "%"UTF8f, UTF8fARG(utf8, l1-1, buf));
 }
 
-/* XXX Here's a total kludge.  But we need to re-enter for swash routines. */
-
-#ifndef PERL_IN_XSUB_RE
-void
-Perl_save_re_context(pTHX)
-{
-    /* Save $1..$n (#18107: UTF-8 s/(\w+)/uc($1)/e); AMS 20021106. */
-    if (PL_curpm) {
-       const REGEXP * const rx = PM_GETRE(PL_curpm);
-       if (rx) {
-           U32 i;
-           for (i = 1; i <= RX_NPARENS(rx); i++) {
-               char digits[TYPE_CHARS(long)];
-               const STRLEN len = my_snprintf(digits, sizeof(digits),
-                                               "%lu", (long)i);
-               GV *const *const gvp
-                   = (GV**)hv_fetch(PL_defstash, digits, len, 0);
-
-               if (gvp) {
-                   GV * const gv = *gvp;
-                   if (SvTYPE(gv) == SVt_PVGV && GvSV(gv))
-                       save_scalar(gv);
-               }
-           }
-       }
-    }
-}
-#endif
-
 #ifdef DEBUGGING
+/* Certain characters are output as a sequence with the first being a
+ * backslash. */
+#define isBACKSLASHED_PUNCT(c)                                              \
+                    ((c) == '-' || (c) == ']' || (c) == '\\' || (c) == '^')
 
 STATIC void
-S_put_byte(pTHX_ SV *sv, int c)
+S_put_code_point(pTHX_ SV *sv, UV c)
 {
-    PERL_ARGS_ASSERT_PUT_BYTE;
-
-    if (!isPRINT(c)) {
-        switch (c) {
-            case '\r': Perl_sv_catpvf(aTHX_ sv, "\\r"); break;
-            case '\n': Perl_sv_catpvf(aTHX_ sv, "\\n"); break;
-            case '\t': Perl_sv_catpvf(aTHX_ sv, "\\t"); break;
-            case '\f': Perl_sv_catpvf(aTHX_ sv, "\\f"); break;
-            case '\a': Perl_sv_catpvf(aTHX_ sv, "\\a"); break;
+    PERL_ARGS_ASSERT_PUT_CODE_POINT;
 
-            default:
-                Perl_sv_catpvf(aTHX_ sv, "\\x{%x}", c);
-                break;
-        }
+    if (c > 255) {
+        Perl_sv_catpvf(aTHX_ sv, "\\x{%04"UVXf"}", c);
     }
-    else {
-       const char string = c;
-       if (c == '-' || c == ']' || c == '\\' || c == '^')
+    else if (isPRINT(c)) {
+       const char string = (char) c;
+       if (isBACKSLASHED_PUNCT(c))
            sv_catpvs(sv, "\\");
        sv_catpvn(sv, &string, 1);
     }
+    else {
+        const char * const mnemonic = cntrl_to_mnemonic((char) c);
+        if (mnemonic) {
+            Perl_sv_catpvf(aTHX_ sv, "%s", mnemonic);
+        }
+        else {
+            Perl_sv_catpvf(aTHX_ sv, "\\x{%02X}", (U8) c);
+        }
+    }
 }
 
+#define MAX_PRINT_A MAX_PRINT_A_FOR_USE_ONLY_BY_REGCOMP_DOT_C
+
 STATIC void
-S_put_range(pTHX_ SV *sv, UV start, UV end)
+S_put_range(pTHX_ SV *sv, UV start, const UV end, const bool allow_literals)
 {
-
     /* Appends to 'sv' a displayable version of the range of code points from
      * 'start' to 'end'.  It assumes that only ASCII printables are displayable
-     * as-is (though some of these will be escaped by put_byte()).  For the
-     * time being, this subroutine only works for latin1 (< 256) code points */
+     * as-is (though some of these will be escaped by put_code_point()). */
+
+    const unsigned int min_range_count = 3;
 
     assert(start <= end);
 
     PERL_ARGS_ASSERT_PUT_RANGE;
 
     while (start <= end) {
-        if (end - start < 3) {  /* Individual chars in short ranges */
+        UV this_end;
+        const char * format;
+
+        if (end - start < min_range_count) {
+
+            /* Individual chars in short ranges */
             for (; start <= end; start++) {
-                put_byte(sv, start);
+                put_code_point(sv, start);
             }
             break;
         }
 
-        /* For small ranges that include printable ASCII characters, it's more
-         * legible to print those characters rather than hex values.  For
-         * larger ranges that include more than printables, it's probably
-         * clearer to just give the start and end points of the range in hex,
-         * and that's all we can do if there aren't any printables within the
-         * range
-         *
-         * On ASCII platforms the range of printables is contiguous.  If the
-         * entire range is printable, we print each character as such.  If the
-         * range is partially printable and partially not, it's less likely
-         * that the individual printables are meaningful, especially if all or
-         * almost all of them are in the range.  But we err on the side of the
-         * individual printables being meaningful by using the hex only if the
-         * range contains all but 2 of the printables.
-         *
-         * On EBCDIC platforms, the printables are scattered around so that the
-         * maximum range length containing only them is about 10.  Anything
-         * longer we treat as hex; otherwise we examine the range character by
-         * character to see */
-#ifdef EBCDIC
-        if (start < 256 && (((end < 255) ? end : 255) - start <= 10))
-#else
-        if ((isPRINT_A(start) && isPRINT_A(end))
-            || (end >= 0x7F && (isPRINT_A(start) && start > 0x21))
-            || ((end < 0x7D && isPRINT_A(end)) && start < 0x20))
-#endif
-        {
-            /* If the range beginning isn't an ASCII printable, we find the
-             * last such in the range, then split the output, so all the
-             * non-printables are in one subrange; then process the remaining
-             * portion as usual.  If the entire range isn't printables, we
-             * don't split, but drop down to print as hex */
+        /* If permitted by the input options, and there is a possibility that
+         * this range contains a printable literal, look to see if there is
+         * one.  */
+        if (allow_literals && start <= MAX_PRINT_A) {
+
+            /* If the range begin isn't an ASCII printable, effectively split
+             * the range into two parts:
+             *  1) the portion before the first such printable,
+             *  2) the rest
+             * and output them separately. */
             if (! isPRINT_A(start)) {
                 UV temp_end = start + 1;
-                while (temp_end <= end && ! isPRINT_A(temp_end)) {
+
+                /* There is no point looking beyond the final possible
+                 * printable, in MAX_PRINT_A */
+                UV max = MIN(end, MAX_PRINT_A);
+
+                while (temp_end <= max && ! isPRINT_A(temp_end)) {
                     temp_end++;
                 }
-                if (temp_end <= end) {
-                    put_range(sv, start, temp_end - 1);
-                    start = temp_end;
-                    continue;
+
+                /* Here, temp_end points to one beyond the first printable if
+                 * found, or to one beyond 'max' if not.  If none found, make
+                 * sure that we use the entire range */
+                if (temp_end > MAX_PRINT_A) {
+                    temp_end = end + 1;
                 }
-            }
 
-            /* If the range beginning is a digit, output a subrange of just the
-             * digits, then process the remaining portion as usual */
-            if (isDIGIT_A(start)) {
-                put_byte(sv, start);
-                sv_catpvs(sv, "-");
-                while (start <= end && isDIGIT_A(start)) start++;
-                put_byte(sv, start - 1);
+                /* Output the first part of the split range, the part that
+                 * doesn't have printables, with no looking for literals
+                 * (otherwise we would infinitely recurse) */
+                put_range(sv, start, temp_end - 1, FALSE);
+
+                /* The 2nd part of the range (if any) starts here. */
+                start = temp_end;
+
+                /* We continue instead of dropping down because even if the 2nd
+                 * part is non-empty, it could be so short that we want to
+                 * output it specially, as tested for at the top of this loop.
+                 * */
                 continue;
             }
 
-            /* Similarly for alphabetics.  Because in both ASCII and EBCDIC,
-             * the code points for upper and lower A-Z and a-z aren't
-             * intermixed, the resulting subrange will consist solely of either
-             * upper- or lower- alphabetics */
-            if (isALPHA_A(start)) {
-                put_byte(sv, start);
-                sv_catpvs(sv, "-");
-                while (start <= end && isALPHA_A(start)) start++;
-                put_byte(sv, start - 1);
+            /* Here, 'start' is a printable ASCII.  If it is an alphanumeric,
+             * output a sub-range of just the digits or letters, then process
+             * the remaining portion as usual. */
+            if (isALPHANUMERIC_A(start)) {
+                UV mask = (isDIGIT_A(start))
+                           ? _CC_DIGIT
+                             : isUPPER_A(start)
+                               ? _CC_UPPER
+                               : _CC_LOWER;
+                UV temp_end = start + 1;
+
+                /* Find the end of the sub-range that includes just the
+                 * characters in the same class as the first character in it */
+                while (temp_end <= end && _generic_isCC_A(temp_end, mask)) {
+                    temp_end++;
+                }
+                temp_end--;
+
+                /* For short ranges, don't duplicate the code above to output
+                 * them; just call recursively */
+                if (temp_end - start < min_range_count) {
+                    put_range(sv, start, temp_end, FALSE);
+                }
+                else {  /* Output as a range */
+                    put_code_point(sv, start);
+                    sv_catpvs(sv, "-");
+                    put_code_point(sv, temp_end);
+                }
+                start = temp_end + 1;
                 continue;
             }
 
-            /* We output any remaining printables as individual characters */
+            /* We output any other printables as individual characters */
             if (isPUNCT_A(start) || isSPACE_A(start)) {
-                while (start <= end && (isPUNCT_A(start) || isSPACE_A(start))) {
-                    put_byte(sv, start);
+                while (start <= end && (isPUNCT_A(start)
+                                        || isSPACE_A(start)))
+                {
+                    put_code_point(sv, start);
                     start++;
                 }
                 continue;
             }
+        } /* End of looking for literals */
+
+        /* Here is not to output as a literal.  Some control characters have
+         * mnemonic names.  Split off any of those at the beginning and end of
+         * the range to print mnemonically.  It isn't possible for many of
+         * these to be in a row, so this won't overwhelm with output */
+        while (isMNEMONIC_CNTRL(start) && start <= end) {
+            put_code_point(sv, start);
+            start++;
         }
+        if (start < end && isMNEMONIC_CNTRL(end)) {
 
-        /* Here is a control or non-ascii.  Output the range or subrange as
-         * hex. */
-        Perl_sv_catpvf(aTHX_ sv, "\\x{%02" UVXf "}-\\x{%02" UVXf "}",
-                       start,
-                       (end < 256) ? end : 255);
+            /* Here, the final character in the range has a mnemonic name.
+             * Work backwards from the end to find the final non-mnemonic */
+            UV temp_end = end - 1;
+            while (isMNEMONIC_CNTRL(temp_end)) {
+                temp_end--;
+            }
+
+            /* And separately output the range that doesn't have mnemonics */
+            put_range(sv, start, temp_end, FALSE);
+
+            /* Then output the mnemonic trailing controls */
+            start = temp_end + 1;
+            while (start <= end) {
+                put_code_point(sv, start);
+                start++;
+            }
+            break;
+        }
+
+        /* As a final resort, output the range or subrange as hex. */
+
+        this_end = (end < NUM_ANYOF_CODE_POINTS)
+                    ? end
+                    : NUM_ANYOF_CODE_POINTS - 1;
+        format = (this_end < 256)
+                 ? "\\x{%02"UVXf"}-\\x{%02"UVXf"}"
+                 : "\\x{%04"UVXf"}-\\x{%04"UVXf"}";
+        GCC_DIAG_IGNORE(-Wformat-nonliteral);
+        Perl_sv_catpvf(aTHX_ sv, format, start, this_end);
+        GCC_DIAG_RESTORE;
         break;
     }
 }
 
 STATIC bool
-S_put_latin1_charclass_innards(pTHX_ SV *sv, char *bitmap)
+S_put_charclass_bitmap_innards(pTHX_ SV *sv, char *bitmap, SV** bitmap_invlist)
 {
     /* Appends to 'sv' a displayable version of the innards of the bracketed
      * character class whose bitmap is 'bitmap';  Returns 'TRUE' if it actually
-     * output anything */
+     * output anything, and bitmap_invlist, if not NULL, will point to an
+     * inversion list of what is in the bit map */
 
     int i;
-    bool has_output_anything = FALSE;
+    UV start, end;
+    unsigned int punct_count = 0;
+    SV* invlist = NULL;
+    SV** invlist_ptr;   /* Temporary, in case bitmap_invlist is NULL */
+    bool allow_literals = TRUE;
+
+    PERL_ARGS_ASSERT_PUT_CHARCLASS_BITMAP_INNARDS;
+
+    invlist_ptr = (bitmap_invlist) ? bitmap_invlist : &invlist;
+
+    /* Worst case is exactly every-other code point is in the list */
+    *invlist_ptr = _new_invlist(NUM_ANYOF_CODE_POINTS / 2);
+
+    /* Convert the bit map to an inversion list, keeping track of how many
+     * ASCII puncts are set, including an extra amount for the backslashed
+     * ones.  */
+    for (i = 0; i < NUM_ANYOF_CODE_POINTS; i++) {
+        if (BITMAP_TEST(bitmap, i)) {
+            *invlist_ptr = add_cp_to_invlist(*invlist_ptr, i);
+            if (isPUNCT_A(i)) {
+                punct_count++;
+                if isBACKSLASHED_PUNCT(i) {
+                    punct_count++;
+                }
+            }
+        }
+    }
 
-    PERL_ARGS_ASSERT_PUT_LATIN1_CHARCLASS_INNARDS;
+    /* Nothing to output */
+    if (_invlist_len(*invlist_ptr) == 0) {
+        SvREFCNT_dec(invlist);
+        return FALSE;
+    }
 
-    for (i = 0; i < 256; i++) {
-        if (BITMAP_TEST((U8 *) bitmap,i)) {
+    /* Generally, it is more readable if printable characters are output as
+     * literals, but if a range (nearly) spans all of them, it's best to output
+     * it as a single range.  This code will use a single range if all but 2
+     * printables are in it */
+    invlist_iterinit(*invlist_ptr);
+    while (invlist_iternext(*invlist_ptr, &start, &end)) {
 
-            /* The character at index i should be output.  Find the next
-             * character that should NOT be output */
-            int j;
-            for (j = i + 1; j < 256; j++) {
-                if (! BITMAP_TEST((U8 *) bitmap, j)) {
-                    break;
-                }
-            }
+        /* If range starts beyond final printable, it doesn't have any in it */
+        if (start > MAX_PRINT_A) {
+            break;
+        }
 
-            /* Everything between them is a single range that should be output
-             * */
-            put_range(sv, i, j - 1);
-            has_output_anything = TRUE;
-            i = j;
+        /* In both ASCII and EBCDIC, a SPACE is the lowest printable.  To span
+         * all but two, the range must start and end no later than 2 from
+         * either end */
+        if (start < ' ' + 2 && end > MAX_PRINT_A - 2) {
+            if (end > MAX_PRINT_A) {
+                end = MAX_PRINT_A;
+            }
+            if (start < ' ') {
+                start = ' ';
+            }
+            if (end - start >= MAX_PRINT_A - ' ' - 2) {
+                allow_literals = FALSE;
+            }
+            break;
         }
     }
+    invlist_iterfinish(*invlist_ptr);
+
+    /* The legibility of the output depends mostly on how many punctuation
+     * characters are output.  There are 32 possible ASCII ones, and some have
+     * an additional backslash, bringing it to currently 36, so if any more
+     * than 18 are to be output, we can instead output it as its complement,
+     * yielding fewer puncts, and making it more legible.  But give some weight
+     * to the fact that outputting it as a complement is less legible than a
+     * straight output, so don't complement unless we are somewhat over the 18
+     * mark */
+    if (allow_literals && punct_count > 22) {
+        sv_catpvs(sv, "^");
+
+        /* Add everything remaining to the list, so when we invert it just
+         * below, it will be excluded */
+        _invlist_union_complement_2nd(*invlist_ptr, PL_InBitmap, invlist_ptr);
+        _invlist_invert(*invlist_ptr);
+    }
+
+    /* Here we have figured things out.  Output each range */
+    invlist_iterinit(*invlist_ptr);
+    while (invlist_iternext(*invlist_ptr, &start, &end)) {
+        if (start >= NUM_ANYOF_CODE_POINTS) {
+            break;
+        }
+        put_range(sv, start, end, allow_literals);
+    }
+    invlist_iterfinish(*invlist_ptr);
 
-    return has_output_anything;
+    return TRUE;
 }
 
 #define CLEAR_OPTSTART \
@@ -16756,7 +17481,7 @@ S_dumpuntil(pTHX_ const regexp *r, const regnode *start, const regnode *node,
        } else
            CLEAR_OPTSTART;
 
-       regprop(r, sv, node, NULL);
+        regprop(r, sv, node, NULL, NULL);
        PerlIO_printf(Perl_debug_log, "%4"IVdf":%*s%s", (IV)(node - start),
                      (int)(2*indent + 1), "", SvPVX_const(sv));
 
@@ -16853,7 +17578,7 @@ S_dumpuntil(pTHX_ const regexp *r, const regnode *start, const regnode *node,
        }
        else if (PL_regkind[(U8)op] == ANYOF) {
            /* arglen 1 + class block */
-           node += 1 + ((ANYOF_FLAGS(node) & ANYOF_POSIXL)
+           node += 1 + ((ANYOF_FLAGS(node) & ANYOF_MATCHES_POSIXL)
                           ? ANYOF_POSIXL_SKIP
                           : ANYOF_SKIP);
            node = NEXTOPER(node);