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Fix typo in comment. mauke- ++.
[perl5.git] / regexec.c
index 18a5cba..5f142a0 100644 (file)
--- a/regexec.c
+++ b/regexec.c
@@ -93,13 +93,6 @@ static const char* const non_utf8_target_but_utf8_required
 #include "inline_invlist.c"
 #include "unicode_constants.h"
 
-#define RF_tainted     1       /* tainted information used? e.g. locale */
-#define RF_warned      2               /* warned about big count? */
-
-#define RF_utf8                8               /* Pattern contains multibyte chars? */
-
-#define UTF_PATTERN ((PL_reg_flags & RF_utf8) != 0)
-
 #define HAS_NONLATIN1_FOLD_CLOSURE(i) _HAS_NONLATIN1_FOLD_CLOSURE_ONLY_FOR_USE_BY_REGCOMP_DOT_C_AND_REGEXEC_DOT_C(i)
 
 #ifndef STATIC
@@ -117,20 +110,21 @@ static const char* const non_utf8_target_but_utf8_required
  */
 
 #define CHR_SVLEN(sv) (utf8_target ? sv_len_utf8(sv) : SvCUR(sv))
-#define CHR_DIST(a,b) (PL_reg_match_utf8 ? utf8_distance(a,b) : a - b)
+#define CHR_DIST(a,b) (reginfo->is_utf8_target ? utf8_distance(a,b) : a - b)
 
 #define HOPc(pos,off) \
-       (char *)(PL_reg_match_utf8 \
-           ? reghop3((U8*)pos, off, (U8*)(off >= 0 ? PL_regeol : PL_bostr)) \
+       (char *)(reginfo->is_utf8_target \
+           ? reghop3((U8*)pos, off, \
+                    (U8*)(off >= 0 ? reginfo->strend : reginfo->strbeg)) \
            : (U8*)(pos + off))
 #define HOPBACKc(pos, off) \
-       (char*)(PL_reg_match_utf8\
-           ? reghopmaybe3((U8*)pos, -off, (U8*)PL_bostr) \
-           : (pos - off >= PL_bostr)           \
+       (char*)(reginfo->is_utf8_target \
+           ? reghopmaybe3((U8*)pos, -off, (U8*)(reginfo->strbeg)) \
+           : (pos - off >= reginfo->strbeg)    \
                ? (U8*)pos - off                \
                : NULL)
 
-#define HOP3(pos,off,lim) (PL_reg_match_utf8 ? reghop3((U8*)(pos), off, (U8*)(lim)) : (U8*)(pos + off))
+#define HOP3(pos,off,lim) (reginfo->is_utf8_target  ? reghop3((U8*)(pos), off, (U8*)(lim)) : (U8*)(pos + off))
 #define HOP3c(pos,off,lim) ((char*)HOP3(pos,off,lim))
 
 
@@ -138,43 +132,52 @@ static const char* const non_utf8_target_but_utf8_required
 #define NEXTCHR_IS_EOS (nextchr < 0)
 
 #define SET_nextchr \
-    nextchr = ((locinput < PL_regeol) ? UCHARAT(locinput) : NEXTCHR_EOS)
+    nextchr = ((locinput < reginfo->strend) ? UCHARAT(locinput) : NEXTCHR_EOS)
 
 #define SET_locinput(p) \
     locinput = (p);  \
     SET_nextchr
 
 
-/* these are unrolled below in the CCC_TRY_XXX defined */
-#define LOAD_UTF8_CHARCLASS(class,str) STMT_START { \
-    if (!CAT2(PL_utf8_,class)) { \
-       bool ok; \
-       ENTER; save_re_context(); \
-       ok=CAT2(is_utf8_,class)((const U8*)str); \
-        PERL_UNUSED_VAR(ok); \
-       assert(ok); assert(CAT2(PL_utf8_,class)); LEAVE; } } STMT_END
-/* Doesn't do an assert to verify that is correct */
-#define LOAD_UTF8_CHARCLASS_NO_CHECK(class) STMT_START { \
-    if (!CAT2(PL_utf8_,class)) { \
-       bool throw_away; \
-        PERL_UNUSED_VAR(throw_away); \
-       ENTER; save_re_context(); \
-       throw_away = CAT2(is_utf8_,class)((const U8*)" "); \
-        PERL_UNUSED_VAR(throw_away); \
-       LEAVE; } } STMT_END
-
-#define LOAD_UTF8_CHARCLASS_ALNUM() LOAD_UTF8_CHARCLASS(alnum,"a")
-#define LOAD_UTF8_CHARCLASS_DIGIT() LOAD_UTF8_CHARCLASS(digit,"0")
-
-#define LOAD_UTF8_CHARCLASS_GCB()  /* Grapheme cluster boundaries */        \
-        /* No asserts are done for some of these, in case called on a   */  \
-        /* Unicode version in which they map to nothing */                  \
-       LOAD_UTF8_CHARCLASS(X_regular_begin, HYPHEN_UTF8);                  \
-       LOAD_UTF8_CHARCLASS(X_extend, COMBINING_GRAVE_ACCENT_UTF8);         \
+#define LOAD_UTF8_CHARCLASS(swash_ptr, property_name) STMT_START {            \
+        if (!swash_ptr) {                                                     \
+            U8 flags = _CORE_SWASH_INIT_ACCEPT_INVLIST;                       \
+            swash_ptr = _core_swash_init("utf8", property_name, &PL_sv_undef, \
+                                         1, 0, NULL, &flags);                 \
+            assert(swash_ptr);                                                \
+        }                                                                     \
+    } STMT_END
 
-#define PLACEHOLDER    /* Something for the preprocessor to grab onto */
+/* If in debug mode, we test that a known character properly matches */
+#ifdef DEBUGGING
+#   define LOAD_UTF8_CHARCLASS_DEBUG_TEST(swash_ptr,                          \
+                                          property_name,                      \
+                                          utf8_char_in_property)              \
+        LOAD_UTF8_CHARCLASS(swash_ptr, property_name);                        \
+        assert(swash_fetch(swash_ptr, (U8 *) utf8_char_in_property, TRUE));
+#else
+#   define LOAD_UTF8_CHARCLASS_DEBUG_TEST(swash_ptr,                          \
+                                          property_name,                      \
+                                          utf8_char_in_property)              \
+        LOAD_UTF8_CHARCLASS(swash_ptr, property_name)
+#endif
 
+#define LOAD_UTF8_CHARCLASS_ALNUM() LOAD_UTF8_CHARCLASS_DEBUG_TEST(           \
+                                        PL_utf8_swash_ptrs[_CC_WORDCHAR],     \
+                                        swash_property_names[_CC_WORDCHAR],   \
+                                        GREEK_SMALL_LETTER_IOTA_UTF8)
+
+#define LOAD_UTF8_CHARCLASS_GCB()  /* Grapheme cluster boundaries */          \
+    STMT_START {                                                              \
+       LOAD_UTF8_CHARCLASS_DEBUG_TEST(PL_utf8_X_regular_begin,               \
+                                       "_X_regular_begin",                    \
+                                       GREEK_SMALL_LETTER_IOTA_UTF8);         \
+       LOAD_UTF8_CHARCLASS_DEBUG_TEST(PL_utf8_X_extend,                      \
+                                       "_X_extend",                           \
+                                       COMBINING_GRAVE_ACCENT_UTF8);          \
+    } STMT_END
 
+#define PLACEHOLDER    /* Something for the preprocessor to grab onto */
 /* TODO: Combine JUMPABLE and HAS_TEXT to cache OP(rn) */
 
 /* for use after a quantifier and before an EXACT-like node -- japhy */
@@ -243,7 +246,12 @@ static const char* const non_utf8_target_but_utf8_required
 #define SCount 11172    /* Length of block */
 #define TCount 28
 
-static void restore_pos(pTHX_ void *arg);
+#define SLAB_FIRST(s) (&(s)->states[0])
+#define SLAB_LAST(s)  (&(s)->states[PERL_REGMATCH_SLAB_SLOTS-1])
+
+static void S_setup_eval_state(pTHX_ regmatch_info *const reginfo);
+static void S_cleanup_regmatch_info_aux(pTHX_ void *arg);
+static regmatch_state * S_push_slab(pTHX);
 
 #define REGCP_PAREN_ELEMS 3
 #define REGCP_OTHER_ELEMS 3
@@ -433,19 +441,21 @@ S_isFOO_lc(pTHX_ const U8 classnum, const U8 character)
     switch ((_char_class_number) classnum) {
         case _CC_ENUM_ALPHANUMERIC: return isALPHANUMERIC_LC(character);
         case _CC_ENUM_ALPHA:     return isALPHA_LC(character);
+        case _CC_ENUM_ASCII:     return isASCII_LC(character);
+        case _CC_ENUM_BLANK:     return isBLANK_LC(character);
+        case _CC_ENUM_CASED:     return isLOWER_LC(character)
+                                        || isUPPER_LC(character);
+        case _CC_ENUM_CNTRL:     return isCNTRL_LC(character);
         case _CC_ENUM_DIGIT:     return isDIGIT_LC(character);
         case _CC_ENUM_GRAPH:     return isGRAPH_LC(character);
         case _CC_ENUM_LOWER:     return isLOWER_LC(character);
         case _CC_ENUM_PRINT:     return isPRINT_LC(character);
+        case _CC_ENUM_PSXSPC:    return isPSXSPC_LC(character);
         case _CC_ENUM_PUNCT:     return isPUNCT_LC(character);
+        case _CC_ENUM_SPACE:     return isSPACE_LC(character);
         case _CC_ENUM_UPPER:     return isUPPER_LC(character);
         case _CC_ENUM_WORDCHAR:  return isWORDCHAR_LC(character);
-        case _CC_ENUM_SPACE:     return isSPACE_LC(character);
-        case _CC_ENUM_BLANK:     return isBLANK_LC(character);
         case _CC_ENUM_XDIGIT:    return isXDIGIT_LC(character);
-        case _CC_ENUM_CNTRL:     return isCNTRL_LC(character);
-        case _CC_ENUM_PSXSPC:    return isPSXSPC_LC(character);
-        case _CC_ENUM_ASCII:     return isASCII_LC(character);
         default:    /* VERTSPACE should never occur in locales */
             Perl_croak(aTHX_ "panic: isFOO_lc() has an unexpected character class '%d'", classnum);
     }
@@ -486,7 +496,9 @@ S_isFOO_utf8_lc(pTHX_ const U8 classnum, const U8* character)
                 swash_property_names[classnum], &PL_sv_undef, 1, 0, NULL, &flags);
         }
 
-        return swash_fetch(PL_utf8_swash_ptrs[classnum], (U8 *) character, TRUE);
+        return cBOOL(swash_fetch(PL_utf8_swash_ptrs[classnum], (U8 *)
+                                 character,
+                                 TRUE /* is UTF */ ));
     }
 
     switch ((_char_class_number) classnum) {
@@ -545,13 +557,9 @@ Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, char *strend,
  * with giant delta may be not rechecked).
  */
 
-/* Assumptions: if ANCH_GPOS, then strpos is anchored. XXXX Check GPOS logic */
-
 /* If SCREAM, then SvPVX_const(sv) should be compatible with strpos and strend.
    Otherwise, only SvCUR(sv) is used to get strbeg. */
 
-/* XXXX We assume that strpos is strbeg unless sv. */
-
 /* XXXX Some places assume that there is a fixed substring.
        An update may be needed if optimizer marks as "INTUITable"
        RExen without fixed substrings.  Similarly, it is assumed that
@@ -565,7 +573,7 @@ Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, char *strend,
 
 /* A failure to find a constant substring means that there is no need to make
    an expensive call to REx engine, thus we celebrate a failure.  Similarly,
-   finding a substring too deep into the string means that less calls to
+   finding a substring too deep into the string means that fewer calls to
    regtry() should be needed.
 
    REx compiler's optimizer found 4 possible hints:
@@ -581,9 +589,29 @@ Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, char *strend,
    The nodes of the REx which we used for the search should have been
    deleted from the finite automaton. */
 
+/* args:
+ * rx:     the regex to match against
+ * sv:     the SV being matched: only used for utf8 flag; the string
+ *         itself is accessed via the pointers below. Note that on
+ *         something like an overloaded SV, SvPOK(sv) may be false
+ *         and the string pointers may point to something unrelated to
+ *         the SV itself.
+ * strbeg: real beginning of string
+ * strpos: the point in the string at which to begin matching
+ * strend: pointer to the byte following the last char of the string
+ * flags   currently unused; set to 0
+ * data:   currently unused; set to NULL
+ */
+
 char *
-Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
-                    char *strend, const U32 flags, re_scream_pos_data *data)
+Perl_re_intuit_start(pTHX_
+                    REGEXP * const rx,
+                    SV *sv,
+                    const char * const strbeg,
+                    char *strpos,
+                    char *strend,
+                    const U32 flags,
+                    re_scream_pos_data *data)
 {
     dVAR;
     struct regexp *const prog = ReANY(rx);
@@ -592,7 +620,6 @@ Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
     I32 end_shift   = 0;
     char *s;
     SV *check;
-    char *strbeg;
     char *t;
     const bool utf8_target = (sv && SvUTF8(sv)) ? 1 : 0; /* if no sv we have to assume bytes */
     I32 ml_anch;
@@ -601,6 +628,8 @@ Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
     char *checked_upto = NULL;          /* how far into the string we have already checked using find_byclass*/
     const I32 multiline = prog->extflags & RXf_PMf_MULTILINE;
     RXi_GET_DECL(prog,progi);
+    regmatch_info reginfo_buf;  /* create some info to pass to find_byclass */
+    regmatch_info *const reginfo = &reginfo_buf;
 #ifdef DEBUGGING
     const char * const i_strpos = strpos;
 #endif
@@ -610,40 +639,22 @@ Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
     PERL_UNUSED_ARG(flags);
     PERL_UNUSED_ARG(data);
 
-    RX_MATCH_UTF8_set(rx,utf8_target);
-
-    if (RX_UTF8(rx)) {
-       PL_reg_flags |= RF_utf8;
-    }
-    DEBUG_EXECUTE_r( 
-        debug_start_match(rx, utf8_target, strpos, strend,
-            sv ? "Guessing start of match in sv for"
-               : "Guessing start of match in string for");
-             );
-
     /* CHR_DIST() would be more correct here but it makes things slow. */
     if (prog->minlen > strend - strpos) {
        DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                              "String too short... [re_intuit_start]\n"));
        goto fail;
     }
-                
-    /* XXX we need to pass strbeg as a separate arg: the following is
-     * guesswork and can be wrong... */
-    if (sv && SvPOK(sv)) {
-        char * p   = SvPVX(sv);
-        STRLEN cur = SvCUR(sv); 
-        if (p <= strpos && strpos < p + cur) {
-            strbeg = p;
-            assert(p <= strend && strend <= p + cur);
-        }
-        else
-            strbeg = strend - cur;
-    }
-    else 
-        strbeg = strpos;
 
-    PL_regeol = strend;
+    reginfo->is_utf8_target = cBOOL(utf8_target);
+    reginfo->info_aux = NULL;
+    reginfo->strbeg = strbeg;
+    reginfo->strend = strend;
+    reginfo->is_utf8_pat = cBOOL(RX_UTF8(rx));
+    reginfo->intuit = 1;
+    /* not actually used within intuit, but zero for safety anyway */
+    reginfo->poscache_maxiter = 0;
+
     if (utf8_target) {
        if (!prog->check_utf8 && prog->check_substr)
            to_utf8_substr(prog);
@@ -656,16 +667,15 @@ Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
         }
        check = prog->check_substr;
     }
-    if (prog->extflags & RXf_ANCH) {   /* Match at beg-of-str or after \n */
-       ml_anch = !( (prog->extflags & RXf_ANCH_SINGLE)
+    if ((prog->extflags & RXf_ANCH)    /* Match at beg-of-str or after \n */
+        && !(prog->extflags & RXf_ANCH_GPOS)) /* \G isn't a BOS or \n */
+    {
+        ml_anch = !( (prog->extflags & RXf_ANCH_SINGLE)
                     || ( (prog->extflags & RXf_ANCH_BOL)
                          && !multiline ) );    /* Check after \n? */
 
        if (!ml_anch) {
-         if ( !(prog->extflags & RXf_ANCH_GPOS) /* Checked by the caller */
-               && !(prog->intflags & PREGf_IMPLICIT) /* not a real BOL */
-              /* SvCUR is not set on references: SvRV and SvPVX_const overlap */
-              && sv && !SvROK(sv)
+         if (    !(prog->intflags & PREGf_IMPLICIT) /* not a real BOL */
               && (strpos != strbeg)) {
              DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Not at start...\n"));
              goto fail;
@@ -1039,8 +1049,7 @@ Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
       try_at_start:
        /* Even in this situation we may use MBOL flag if strpos is offset
           wrt the start of the string. */
-       if (ml_anch && sv && !SvROK(sv) /* See prev comment on SvROK */
-           && (strpos != strbeg) && strpos[-1] != '\n'
+       if (ml_anch && (strpos != strbeg) && strpos[-1] != '\n'
            /* May be due to an implicit anchor of m{.*foo}  */
            && !(prog->intflags & PREGf_IMPLICIT))
        {
@@ -1100,8 +1109,11 @@ Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
        /* If regstclass takes bytelength more than 1: If charlength==1, OK.
           This leaves EXACTF-ish only, which are dealt with in find_byclass().  */
         const U8* const str = (U8*)STRING(progi->regstclass);
+        /* XXX this value could be pre-computed */
         const int cl_l = (PL_regkind[OP(progi->regstclass)] == EXACT
-                   ? CHR_DIST(str+STR_LEN(progi->regstclass), str)
+                   ?  (reginfo->is_utf8_pat
+                        ? utf8_distance(str + STR_LEN(progi->regstclass), str)
+                        : STR_LEN(progi->regstclass))
                    : 1);
        char * endpos;
        if (prog->anchored_substr || prog->anchored_utf8 || ml_anch)
@@ -1117,7 +1129,8 @@ Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
                                       (IV)start_shift, (IV)(check_at - strbeg), (IV)(s - strbeg), (IV)(endpos - strbeg), (IV)(checked_upto- strbeg)));
 
        t = s;
-        s = find_byclass(prog, progi->regstclass, checked_upto, endpos, NULL);
+        s = find_byclass(prog, progi->regstclass, checked_upto, endpos,
+                            reginfo);
        if (s) {
            checked_upto = s;
        } else {
@@ -1219,8 +1232,8 @@ Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
                               ? (utf8_target ? trie_utf8 : trie_plain) \
                               : (utf8_target ? trie_utf8_fold : trie_latin_utf8_fold))
 
-#define REXEC_TRIE_READ_CHAR(trie_type, trie, widecharmap, uc, uscan, len,          \
-uvc, charid, foldlen, foldbuf, uniflags) STMT_START {                               \
+#define REXEC_TRIE_READ_CHAR(trie_type, trie, widecharmap, uc, uscan, len, uvc, charid, foldlen, foldbuf, uniflags) \
+STMT_START {                               \
     STRLEN skiplen;                                                                 \
     switch (trie_type) {                                                            \
     case trie_utf8_fold:                                                            \
@@ -1245,7 +1258,7 @@ uvc, charid, foldlen, foldbuf, uniflags) STMT_START {
             len=0;                                                                  \
         } else {                                                                    \
             len = 1;                                                                \
-            uvc = _to_fold_latin1( (U8) *uc, foldbuf, &foldlen, 1);                 \
+            uvc = _to_fold_latin1( (U8) *uc, foldbuf, &foldlen, FOLD_FLAGS_FULL);   \
             skiplen = UNISKIP( uvc );                                               \
             foldlen -= skiplen;                                                     \
             uscan = foldbuf + skiplen;                                              \
@@ -1277,7 +1290,7 @@ STMT_START {                                              \
     while (s <= e) {                                      \
        if ( (CoNd)                                       \
             && (ln == 1 || folder(s, pat_string, ln))    \
-            && (!reginfo || regtry(reginfo, &s)) )       \
+            && (reginfo->intuit || regtry(reginfo, &s)) )\
            goto got_it;                                  \
        s++;                                              \
     }                                                     \
@@ -1302,7 +1315,7 @@ STMT_START {                                          \
 #define REXEC_FBC_UTF8_CLASS_SCAN(CoNd)               \
 REXEC_FBC_UTF8_SCAN(                                  \
     if (CoNd) {                                       \
-       if (tmp && (!reginfo || regtry(reginfo, &s))) \
+       if (tmp && (reginfo->intuit || regtry(reginfo, &s))) \
            goto got_it;                              \
        else                                          \
            tmp = doevery;                            \
@@ -1314,7 +1327,7 @@ REXEC_FBC_UTF8_SCAN(                                  \
 #define REXEC_FBC_CLASS_SCAN(CoNd)                    \
 REXEC_FBC_SCAN(                                       \
     if (CoNd) {                                       \
-       if (tmp && (!reginfo || regtry(reginfo, &s)))  \
+       if (tmp && (reginfo->intuit || regtry(reginfo, &s)))  \
            goto got_it;                              \
        else                                          \
            tmp = doevery;                            \
@@ -1324,7 +1337,7 @@ REXEC_FBC_SCAN(                                       \
 )
 
 #define REXEC_FBC_TRYIT               \
-if ((!reginfo || regtry(reginfo, &s))) \
+if ((reginfo->intuit || regtry(reginfo, &s))) \
     goto got_it
 
 #define REXEC_FBC_CSCAN(CoNdUtF8,CoNd)                         \
@@ -1336,11 +1349,12 @@ if ((!reginfo || regtry(reginfo, &s))) \
     }
     
 #define DUMP_EXEC_POS(li,s,doutf8) \
-    dump_exec_pos(li,s,(PL_regeol),(PL_bostr),(PL_reg_starttry),doutf8)
+    dump_exec_pos(li,s,(reginfo->strend),(reginfo->strbeg), \
+                startpos, doutf8)
 
 
 #define UTF8_NOLOAD(TEST_NON_UTF8, IF_SUCCESS, IF_FAIL) \
-       tmp = (s != PL_bostr) ? UCHARAT(s - 1) : '\n';                         \
+       tmp = (s != reginfo->strbeg) ? UCHARAT(s - 1) : '\n';                  \
        tmp = TEST_NON_UTF8(tmp);                                              \
        REXEC_FBC_UTF8_SCAN(                                                   \
            if (tmp == ! TEST_NON_UTF8((U8) *s)) { \
@@ -1353,11 +1367,11 @@ if ((!reginfo || regtry(reginfo, &s))) \
        );                                                                     \
 
 #define UTF8_LOAD(TeSt1_UtF8, TeSt2_UtF8, IF_SUCCESS, IF_FAIL) \
-       if (s == PL_bostr) {                                                   \
+       if (s == reginfo->strbeg) {                                            \
            tmp = '\n';                                                        \
        }                                                                      \
        else {                                                                 \
-           U8 * const r = reghop3((U8*)s, -1, (U8*)PL_bostr);                 \
+           U8 * const r = reghop3((U8*)s, -1, (U8*)reginfo->strbeg);          \
            tmp = utf8n_to_uvchr(r, UTF8SKIP(r), 0, UTF8_ALLOW_DEFAULT);       \
        }                                                                      \
        tmp = TeSt1_UtF8;                                                      \
@@ -1403,7 +1417,7 @@ if ((!reginfo || regtry(reginfo, &s))) \
                UTF8_CODE \
     }                                                                          \
     else {  /* Not utf8 */                                                     \
-       tmp = (s != PL_bostr) ? UCHARAT(s - 1) : '\n';                         \
+       tmp = (s != reginfo->strbeg) ? UCHARAT(s - 1) : '\n';                  \
        tmp = TEST_NON_UTF8(tmp);                                              \
        REXEC_FBC_SCAN(                                                        \
            if (tmp == ! TEST_NON_UTF8((U8) *s)) {                             \
@@ -1415,11 +1429,11 @@ if ((!reginfo || regtry(reginfo, &s))) \
            }                                                                  \
        );                                                                     \
     }                                                                          \
-    if ((!prog->minlen && tmp) && (!reginfo || regtry(reginfo, &s)))           \
+    if ((!prog->minlen && tmp) && (reginfo->intuit || regtry(reginfo, &s)))           \
        goto got_it;
 
 /* We know what class REx starts with.  Try to find this position... */
-/* if reginfo is NULL, its a dryrun */
+/* if reginfo->intuit, its a dryrun */
 /* annoyingly all the vars in this routine have different names from their counterparts
    in regmatch. /grrr */
 
@@ -1439,8 +1453,9 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
     U8 c2;
     char *e;
     I32 tmp = 1;       /* Scratch variable? */
-    const bool utf8_target = PL_reg_match_utf8;
+    const bool utf8_target = reginfo->is_utf8_target;
     UV utf8_fold_flags = 0;
+    const bool is_utf8_pat = reginfo->is_utf8_pat;
     bool to_complement = FALSE; /* Invert the result?  Taking the xor of this
                                    with a result inverts that result, as 0^1 =
                                    1 and 1^1 = 0 */
@@ -1453,6 +1468,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
     /* We know what class it must start with. */
     switch (OP(c)) {
     case ANYOF:
+    case ANYOF_SYNTHETIC:
+    case ANYOF_WARN_SUPER:
         if (utf8_target) {
             REXEC_FBC_UTF8_CLASS_SCAN(
                       reginclass(prog, c, (U8*)s, utf8_target));
@@ -1463,7 +1480,7 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
         break;
     case CANY:
         REXEC_FBC_SCAN(
-            if (tmp && (!reginfo || regtry(reginfo, &s)))
+            if (tmp && (reginfo->intuit || regtry(reginfo, &s)))
                 goto got_it;
             else
                 tmp = doevery;
@@ -1471,7 +1488,7 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
         break;
 
     case EXACTFA:
-        if (UTF_PATTERN || utf8_target) {
+        if (is_utf8_pat || utf8_target) {
             utf8_fold_flags = FOLDEQ_UTF8_NOMIX_ASCII;
             goto do_exactf_utf8;
         }
@@ -1491,7 +1508,7 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
         goto do_exactf_non_utf8;
 
     case EXACTFL:
-        if (UTF_PATTERN || utf8_target) {
+        if (is_utf8_pat || utf8_target) {
             utf8_fold_flags = FOLDEQ_UTF8_LOCALE;
             goto do_exactf_utf8;
         }
@@ -1500,15 +1517,15 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
         goto do_exactf_non_utf8;
 
     case EXACTFU_SS:
-        if (UTF_PATTERN) {
+        if (is_utf8_pat) {
             utf8_fold_flags = FOLDEQ_S2_ALREADY_FOLDED;
         }
         goto do_exactf_utf8;
 
     case EXACTFU_TRICKYFOLD:
     case EXACTFU:
-        if (UTF_PATTERN || utf8_target) {
-            utf8_fold_flags = (UTF_PATTERN) ? FOLDEQ_S2_ALREADY_FOLDED : 0;
+        if (is_utf8_pat || utf8_target) {
+            utf8_fold_flags = is_utf8_pat ? FOLDEQ_S2_ALREADY_FOLDED : 0;
             goto do_exactf_utf8;
         }
 
@@ -1540,7 +1557,7 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
          * required minimum number from the far end */
         e = HOP3c(strend, -((I32)ln), s);
 
-        if (!reginfo && e < s) {
+        if (reginfo->intuit && e < s) {
             e = s;                     /* Due to minlen logic of intuit() */
         }
 
@@ -1564,7 +1581,7 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
         pat_string = STRING(c);
         ln  = STR_LEN(c);      /* length to match in octets/bytes */
         pat_end = pat_string + ln;
-        lnc = (UTF_PATTERN)     /* length to match in characters */
+        lnc = is_utf8_pat       /* length to match in characters */
                 ? utf8_length((U8 *) pat_string, (U8 *) pat_end)
                 : ln;
 
@@ -1586,7 +1603,7 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
          */
         e = HOP3c(strend, -((I32)lnc), s);
 
-        if (!reginfo && e < s) {
+        if (reginfo->intuit && e < s) {
             e = s;                     /* Due to minlen logic of intuit() */
         }
 
@@ -1600,8 +1617,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
         while (s <= e) {
             char *my_strend= (char *)strend;
             if (foldEQ_utf8_flags(s, &my_strend, 0,  utf8_target,
-                  pat_string, NULL, ln, cBOOL(UTF_PATTERN), utf8_fold_flags)
-                && (!reginfo || regtry(reginfo, &s)) )
+                  pat_string, NULL, ln, is_utf8_pat, utf8_fold_flags)
+                && (reginfo->intuit || regtry(reginfo, &s)) )
             {
                 goto got_it;
             }
@@ -1610,21 +1627,21 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
         break;
     }
     case BOUNDL:
-        PL_reg_flags |= RF_tainted;
-        FBC_BOUND(isALNUM_LC,
-                  isALNUM_LC_uvchr(UNI_TO_NATIVE(tmp)),
-                  isALNUM_LC_utf8((U8*)s));
+        RXp_MATCH_TAINTED_on(prog);
+        FBC_BOUND(isWORDCHAR_LC,
+                  isWORDCHAR_LC_uvchr(UNI_TO_NATIVE(tmp)),
+                  isWORDCHAR_LC_utf8((U8*)s));
         break;
     case NBOUNDL:
-        PL_reg_flags |= RF_tainted;
-        FBC_NBOUND(isALNUM_LC,
-                   isALNUM_LC_uvchr(UNI_TO_NATIVE(tmp)),
-                   isALNUM_LC_utf8((U8*)s));
+        RXp_MATCH_TAINTED_on(prog);
+        FBC_NBOUND(isWORDCHAR_LC,
+                   isWORDCHAR_LC_uvchr(UNI_TO_NATIVE(tmp)),
+                   isWORDCHAR_LC_utf8((U8*)s));
         break;
     case BOUND:
         FBC_BOUND(isWORDCHAR,
-                  isALNUM_uni(tmp),
-                  cBOOL(swash_fetch(PL_utf8_alnum, (U8*)s, utf8_target)));
+                  isWORDCHAR_uni(tmp),
+                  cBOOL(swash_fetch(PL_utf8_swash_ptrs[_CC_WORDCHAR], (U8*)s, utf8_target)));
         break;
     case BOUNDA:
         FBC_BOUND_NOLOAD(isWORDCHAR_A,
@@ -1633,8 +1650,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
         break;
     case NBOUND:
         FBC_NBOUND(isWORDCHAR,
-                   isALNUM_uni(tmp),
-                   cBOOL(swash_fetch(PL_utf8_alnum, (U8*)s, utf8_target)));
+                   isWORDCHAR_uni(tmp),
+                   cBOOL(swash_fetch(PL_utf8_swash_ptrs[_CC_WORDCHAR], (U8*)s, utf8_target)));
         break;
     case NBOUNDA:
         FBC_NBOUND_NOLOAD(isWORDCHAR_A,
@@ -1643,13 +1660,13 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
         break;
     case BOUNDU:
         FBC_BOUND(isWORDCHAR_L1,
-                  isALNUM_uni(tmp),
-                  cBOOL(swash_fetch(PL_utf8_alnum, (U8*)s, utf8_target)));
+                  isWORDCHAR_uni(tmp),
+                  cBOOL(swash_fetch(PL_utf8_swash_ptrs[_CC_WORDCHAR], (U8*)s, utf8_target)));
         break;
     case NBOUNDU:
         FBC_NBOUND(isWORDCHAR_L1,
-                   isALNUM_uni(tmp),
-                   cBOOL(swash_fetch(PL_utf8_alnum, (U8*)s, utf8_target)));
+                   isWORDCHAR_uni(tmp),
+                   cBOOL(swash_fetch(PL_utf8_swash_ptrs[_CC_WORDCHAR], (U8*)s, utf8_target)));
         break;
     case LNBREAK:
         REXEC_FBC_CSCAN(is_LNBREAK_utf8_safe(s, strend),
@@ -1665,7 +1682,7 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
         /* FALLTHROUGH */
 
     case POSIXL:
-        PL_reg_flags |= RF_tainted;
+        RXp_MATCH_TAINTED_on(prog);
         REXEC_FBC_CSCAN(to_complement ^ cBOOL(isFOO_utf8_lc(FLAGS(c), (U8 *) s)),
                         to_complement ^ cBOOL(isFOO_lc(FLAGS(c), *s)));
         break;
@@ -1732,7 +1749,7 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
                                 _generic_isCC(TWO_BYTE_UTF8_TO_UNI(*s, *(s + 1)),
                                               classnum))))
                     {
-                        if (tmp && (!reginfo || regtry(reginfo, &s)))
+                        if (tmp && (reginfo->intuit || regtry(reginfo, &s)))
                             goto got_it;
                         else {
                             tmp = doevery;
@@ -2002,7 +2019,7 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
                             (UV)accepted_word, (IV)(s - real_start)
                         );
                     });
-                    if (!reginfo || regtry(reginfo, &s)) {
+                    if (reginfo->intuit || regtry(reginfo, &s)) {
                         FREETMPS;
                         LEAVE;
                         goto got_it;
@@ -2030,6 +2047,155 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
     return s;
 }
 
+/* set RX_SAVED_COPY, RX_SUBBEG etc.
+ * flags have same meanings as with regexec_flags() */
+
+static void
+S_reg_set_capture_string(pTHX_ REGEXP * const rx,
+                            char *strbeg,
+                            char *strend,
+                            SV *sv,
+                            U32 flags,
+                            bool utf8_target)
+{
+    struct regexp *const prog = ReANY(rx);
+
+    if (flags & REXEC_COPY_STR) {
+#ifdef PERL_ANY_COW
+        if (SvCANCOW(sv)) {
+            if (DEBUG_C_TEST) {
+                PerlIO_printf(Perl_debug_log,
+                              "Copy on write: regexp capture, type %d\n",
+                              (int) SvTYPE(sv));
+            }
+            /* Create a new COW SV to share the match string and store
+             * in saved_copy, unless the current COW SV in saved_copy
+             * is valid and suitable for our purpose */
+            if ((   prog->saved_copy
+                 && SvIsCOW(prog->saved_copy)
+                 && SvPOKp(prog->saved_copy)
+                 && SvIsCOW(sv)
+                 && SvPOKp(sv)
+                 && SvPVX(sv) == SvPVX(prog->saved_copy)))
+            {
+                /* just reuse saved_copy SV */
+                if (RXp_MATCH_COPIED(prog)) {
+                    Safefree(prog->subbeg);
+                    RXp_MATCH_COPIED_off(prog);
+                }
+            }
+            else {
+                /* create new COW SV to share string */
+                RX_MATCH_COPY_FREE(rx);
+                prog->saved_copy = sv_setsv_cow(prog->saved_copy, sv);
+            }
+            prog->subbeg = (char *)SvPVX_const(prog->saved_copy);
+            assert (SvPOKp(prog->saved_copy));
+            prog->sublen  = strend - strbeg;
+            prog->suboffset = 0;
+            prog->subcoffset = 0;
+        } else
+#endif
+        {
+            I32 min = 0;
+            I32 max = strend - strbeg;
+            I32 sublen;
+
+            if (    (flags & REXEC_COPY_SKIP_POST)
+                && !(prog->extflags & RXf_PMf_KEEPCOPY) /* //p */
+                && !(PL_sawampersand & SAWAMPERSAND_RIGHT)
+            ) { /* don't copy $' part of string */
+                U32 n = 0;
+                max = -1;
+                /* calculate the right-most part of the string covered
+                 * by a capture. Due to look-ahead, this may be to
+                 * the right of $&, so we have to scan all captures */
+                while (n <= prog->lastparen) {
+                    if (prog->offs[n].end > max)
+                        max = prog->offs[n].end;
+                    n++;
+                }
+                if (max == -1)
+                    max = (PL_sawampersand & SAWAMPERSAND_LEFT)
+                            ? prog->offs[0].start
+                            : 0;
+                assert(max >= 0 && max <= strend - strbeg);
+            }
+
+            if (    (flags & REXEC_COPY_SKIP_PRE)
+                && !(prog->extflags & RXf_PMf_KEEPCOPY) /* //p */
+                && !(PL_sawampersand & SAWAMPERSAND_LEFT)
+            ) { /* don't copy $` part of string */
+                U32 n = 0;
+                min = max;
+                /* calculate the left-most part of the string covered
+                 * by a capture. Due to look-behind, this may be to
+                 * the left of $&, so we have to scan all captures */
+                while (min && n <= prog->lastparen) {
+                    if (   prog->offs[n].start != -1
+                        && prog->offs[n].start < min)
+                    {
+                        min = prog->offs[n].start;
+                    }
+                    n++;
+                }
+                if ((PL_sawampersand & SAWAMPERSAND_RIGHT)
+                    && min >  prog->offs[0].end
+                )
+                    min = prog->offs[0].end;
+
+            }
+
+            assert(min >= 0 && min <= max && min <= strend - strbeg);
+            sublen = max - min;
+
+            if (RX_MATCH_COPIED(rx)) {
+                if (sublen > prog->sublen)
+                    prog->subbeg =
+                            (char*)saferealloc(prog->subbeg, sublen+1);
+            }
+            else
+                prog->subbeg = (char*)safemalloc(sublen+1);
+            Copy(strbeg + min, prog->subbeg, sublen, char);
+            prog->subbeg[sublen] = '\0';
+            prog->suboffset = min;
+            prog->sublen = sublen;
+            RX_MATCH_COPIED_on(rx);
+        }
+        prog->subcoffset = prog->suboffset;
+        if (prog->suboffset && utf8_target) {
+            /* Convert byte offset to chars.
+             * XXX ideally should only compute this if @-/@+
+             * has been seen, a la PL_sawampersand ??? */
+
+            /* If there's a direct correspondence between the
+             * string which we're matching and the original SV,
+             * then we can use the utf8 len cache associated with
+             * the SV. In particular, it means that under //g,
+             * sv_pos_b2u() will use the previously cached
+             * position to speed up working out the new length of
+             * subcoffset, rather than counting from the start of
+             * the string each time. This stops
+             *   $x = "\x{100}" x 1E6; 1 while $x =~ /(.)/g;
+             * from going quadratic */
+            if (SvPOKp(sv) && SvPVX(sv) == strbeg)
+                sv_pos_b2u(sv, &(prog->subcoffset));
+            else
+                prog->subcoffset = utf8_length((U8*)strbeg,
+                                    (U8*)(strbeg+prog->suboffset));
+        }
+    }
+    else {
+        RX_MATCH_COPY_FREE(rx);
+        prog->subbeg = strbeg;
+        prog->suboffset = 0;
+        prog->subcoffset = 0;
+        prog->sublen = strend - strbeg;
+    }
+}
+
+
+
 
 /*
  - regexec_flags - match a regexp against a string
@@ -2044,123 +2210,245 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
 /* sv:        SV being matched: only used for utf8 flag, pos() etc; string
  *            itself is accessed via the pointers above */
 /* data:      May be used for some additional optimizations.
-              Currently its only used, with a U32 cast, for transmitting
-              the ganch offset when doing a /g match. This will change */
-/* nosave:    For optimizations. */
+              Currently unused. */
+/* flags:     For optimizations. See REXEC_* in regexp.h */
 
 {
     dVAR;
     struct regexp *const prog = ReANY(rx);
     char *s;
     regnode *c;
-    char *startpos = stringarg;
+    char *startpos;
     I32 minlen;                /* must match at least this many chars */
     I32 dontbother = 0;        /* how many characters not to try at end */
     I32 end_shift = 0;                 /* Same for the end. */         /* CC */
-    I32 scream_pos = -1;               /* Internal iterator of scream. */
-    char *scream_olds = NULL;
     const bool utf8_target = cBOOL(DO_UTF8(sv));
     I32 multiline;
     RXi_GET_DECL(prog,progi);
-    regmatch_info reginfo;  /* create some info to pass to regtry etc */
+    regmatch_info reginfo_buf;  /* create some info to pass to regtry etc */
+    regmatch_info *const reginfo = &reginfo_buf;
     regexp_paren_pair *swap = NULL;
+    I32 oldsave;
     GET_RE_DEBUG_FLAGS_DECL;
 
     PERL_ARGS_ASSERT_REGEXEC_FLAGS;
     PERL_UNUSED_ARG(data);
 
     /* Be paranoid... */
-    if (prog == NULL || startpos == NULL) {
+    if (prog == NULL || stringarg == NULL) {
        Perl_croak(aTHX_ "NULL regexp parameter");
        return 0;
     }
 
-    multiline = prog->extflags & RXf_PMf_MULTILINE;
-    reginfo.prog = rx;  /* Yes, sorry that this is confusing.  */
-
-    RX_MATCH_UTF8_set(rx, utf8_target);
-    DEBUG_EXECUTE_r( 
-        debug_start_match(rx, utf8_target, startpos, strend,
+    DEBUG_EXECUTE_r(
+        debug_start_match(rx, utf8_target, stringarg, strend,
         "Matching");
     );
 
+    startpos = stringarg;
+
+    if (prog->extflags & RXf_GPOS_SEEN) {
+        MAGIC *mg;
+
+        /* set reginfo->ganch, the position where \G can match */
+
+        reginfo->ganch =
+            (flags & REXEC_IGNOREPOS)
+            ? stringarg /* use start pos rather than pos() */
+            : (sv && (mg = mg_find_mglob(sv)) && mg->mg_len >= 0)
+            ? strbeg + mg->mg_len /* Defined pos() */
+            : strbeg; /* pos() not defined; use start of string */
+
+        DEBUG_GPOS_r(PerlIO_printf(Perl_debug_log,
+            "GPOS ganch set to strbeg[%"IVdf"]\n", reginfo->ganch - strbeg));
+
+        /* in the presence of \G, we may need to start looking earlier in
+         * the string than the suggested start point of stringarg:
+         * if gofs->prog is set, then that's a known, fixed minimum
+         * offset, such as
+         * /..\G/:   gofs = 2
+         * /ab|c\G/: gofs = 1
+         * or if the minimum offset isn't known, then we have to go back
+         * to the start of the string, e.g. /w+\G/
+         */
+
+        if (prog->extflags & RXf_ANCH_GPOS) {
+            startpos  = reginfo->ganch - prog->gofs;
+            if (startpos <
+                ((flags & REXEC_FAIL_ON_UNDERFLOW) ? stringarg : strbeg))
+            {
+                DEBUG_r(PerlIO_printf(Perl_debug_log,
+                        "fail: ganch-gofs before earliest possible start\n"));
+                return 0;
+            }
+        }
+        else if (prog->gofs) {
+            if (startpos - prog->gofs < strbeg)
+                startpos = strbeg;
+            else
+                startpos -= prog->gofs;
+        }
+        else if (prog->extflags & RXf_GPOS_FLOAT)
+            startpos = strbeg;
+    }
+
     minlen = prog->minlen;
+    if ((startpos + minlen) > strend || startpos < strbeg) {
+        DEBUG_r(PerlIO_printf(Perl_debug_log,
+                    "Regex match can't succeed, so not even tried\n"));
+        return 0;
+    }
+
+    /* at the end of this function, we'll do a LEAVE_SCOPE(oldsave),
+     * which will call destuctors to reset PL_regmatch_state, free higher
+     * PL_regmatch_slabs, and clean up regmatch_info_aux and
+     * regmatch_info_aux_eval */
+
+    oldsave = PL_savestack_ix;
+
+    s = startpos;
+
+    if ((prog->extflags & RXf_USE_INTUIT)
+        && !(flags & REXEC_CHECKED))
+    {
+       s = re_intuit_start(rx, sv, strbeg, startpos, strend,
+                                    flags, NULL);
+       if (!s)
+           return 0;
+
+       if (prog->extflags & RXf_CHECK_ALL) {
+            /* we can match based purely on the result of INTUIT.
+             * Set up captures etc just for $& and $-[0]
+             * (an intuit-only match wont have $1,$2,..) */
+            assert(!prog->nparens);
+
+            /* s/// doesn't like it if $& is earlier than where we asked it to
+             * start searching (which can happen on something like /.\G/) */
+            if (       (flags & REXEC_FAIL_ON_UNDERFLOW)
+                    && (s < stringarg))
+            {
+                /* this should only be possible under \G */
+                assert(prog->extflags & RXf_GPOS_SEEN);
+                DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+                    "matched, but failing for REXEC_FAIL_ON_UNDERFLOW\n"));
+                goto phooey;
+            }
+
+            /* match via INTUIT shouldn't have any captures.
+             * Let @-, @+, $^N know */
+            prog->lastparen = prog->lastcloseparen = 0;
+            RX_MATCH_UTF8_set(rx, utf8_target);
+            prog->offs[0].start = s - strbeg;
+            prog->offs[0].end = utf8_target
+                ? (char*)utf8_hop((U8*)s, prog->minlenret) - strbeg
+                : s - strbeg + prog->minlenret;
+            if ( !(flags & REXEC_NOT_FIRST) )
+                S_reg_set_capture_string(aTHX_ rx,
+                                        strbeg, strend,
+                                        sv, flags, utf8_target);
+
+           return 1;
+        }
+    }
+
+    multiline = prog->extflags & RXf_PMf_MULTILINE;
     
-    if (strend - startpos < (minlen+(prog->check_offset_min<0?prog->check_offset_min:0))) {
+    if (strend - s < (minlen+(prog->check_offset_min<0?prog->check_offset_min:0))) {
         DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                              "String too short [regexec_flags]...\n"));
        goto phooey;
     }
-
     
     /* Check validity of program. */
     if (UCHARAT(progi->program) != REG_MAGIC) {
        Perl_croak(aTHX_ "corrupted regexp program");
     }
 
-    PL_reg_flags = 0;
-    PL_reg_state.re_state_eval_setup_done = FALSE;
-    PL_reg_maxiter = 0;
+    RX_MATCH_TAINTED_off(rx);
+
+    reginfo->prog = rx;         /* Yes, sorry that this is confusing.  */
+    reginfo->intuit = 0;
+    reginfo->is_utf8_target = cBOOL(utf8_target);
+    reginfo->is_utf8_pat = cBOOL(RX_UTF8(rx));
+    reginfo->warned = FALSE;
+    reginfo->strbeg  = strbeg;
+    reginfo->sv = sv;
+    reginfo->poscache_maxiter = 0; /* not yet started a countdown */
+    reginfo->strend = strend;
+    /* see how far we have to get to not match where we matched before */
+    reginfo->till = stringarg + minend;
+
+    if (prog->extflags & RXf_EVAL_SEEN && SvPADTMP(sv) && !IS_PADGV(sv)) {
+        /* SAVEFREESV, not sv_mortalcopy, as this SV must last until after
+           S_cleanup_regmatch_info_aux has executed (registered by
+           SAVEDESTRUCTOR_X below).  S_cleanup_regmatch_info_aux modifies
+           magic belonging to this SV.
+           Not newSVsv, either, as it does not COW.
+        */
+        reginfo->sv = newSV(0);
+        sv_setsv(reginfo->sv, sv);
+        SAVEFREESV(reginfo->sv);
+    }
 
-    if (RX_UTF8(rx))
-       PL_reg_flags |= RF_utf8;
+    /* reserve next 2 or 3 slots in PL_regmatch_state:
+     * slot N+0: may currently be in use: skip it
+     * slot N+1: use for regmatch_info_aux struct
+     * slot N+2: use for regmatch_info_aux_eval struct if we have (?{})'s
+     * slot N+3: ready for use by regmatch()
+     */
 
-    /* Mark beginning of line for ^ and lookbehind. */
-    reginfo.bol = startpos; /* XXX not used ??? */
-    PL_bostr  = strbeg;
-    reginfo.sv = sv;
+    {
+        regmatch_state *old_regmatch_state;
+        regmatch_slab  *old_regmatch_slab;
+        int i, max = (prog->extflags & RXf_EVAL_SEEN) ? 2 : 1;
+
+        /* on first ever match, allocate first slab */
+        if (!PL_regmatch_slab) {
+            Newx(PL_regmatch_slab, 1, regmatch_slab);
+            PL_regmatch_slab->prev = NULL;
+            PL_regmatch_slab->next = NULL;
+            PL_regmatch_state = SLAB_FIRST(PL_regmatch_slab);
+        }
 
-    /* Mark end of line for $ (and such) */
-    PL_regeol = strend;
+        old_regmatch_state = PL_regmatch_state;
+        old_regmatch_slab  = PL_regmatch_slab;
 
-    /* see how far we have to get to not match where we matched before */
-    reginfo.till = startpos+minend;
+        for (i=0; i <= max; i++) {
+            if (i == 1)
+                reginfo->info_aux = &(PL_regmatch_state->u.info_aux);
+            else if (i ==2)
+                reginfo->info_aux_eval =
+                reginfo->info_aux->info_aux_eval =
+                            &(PL_regmatch_state->u.info_aux_eval);
 
-    /* If there is a "must appear" string, look for it. */
-    s = startpos;
+            if (++PL_regmatch_state >  SLAB_LAST(PL_regmatch_slab))
+                PL_regmatch_state = S_push_slab(aTHX);
+        }
 
-    if (prog->extflags & RXf_GPOS_SEEN) { /* Need to set reginfo->ganch */
-       MAGIC *mg;
-       if (flags & REXEC_IGNOREPOS){   /* Means: check only at start */
-           reginfo.ganch = startpos + prog->gofs;
-           DEBUG_GPOS_r(PerlIO_printf(Perl_debug_log,
-             "GPOS IGNOREPOS: reginfo.ganch = startpos + %"UVxf"\n",(UV)prog->gofs));
-       } else if (sv && SvTYPE(sv) >= SVt_PVMG
-                 && SvMAGIC(sv)
-                 && (mg = mg_find(sv, PERL_MAGIC_regex_global))
-                 && mg->mg_len >= 0) {
-           reginfo.ganch = strbeg + mg->mg_len;        /* Defined pos() */
-           DEBUG_GPOS_r(PerlIO_printf(Perl_debug_log,
-               "GPOS MAGIC: reginfo.ganch = strbeg + %"IVdf"\n",(IV)mg->mg_len));
-
-           if (prog->extflags & RXf_ANCH_GPOS) {
-               if (s > reginfo.ganch)
-                   goto phooey;
-               s = reginfo.ganch - prog->gofs;
-               DEBUG_GPOS_r(PerlIO_printf(Perl_debug_log,
-                    "GPOS ANCH_GPOS: s = ganch - %"UVxf"\n",(UV)prog->gofs));
-               if (s < strbeg)
-                   goto phooey;
-           }
-       }
-       else if (data) {
-           reginfo.ganch = strbeg + PTR2UV(data);
-            DEBUG_GPOS_r(PerlIO_printf(Perl_debug_log,
-                "GPOS DATA: reginfo.ganch= strbeg + %"UVxf"\n",PTR2UV(data)));
-
-       } else {                                /* pos() not defined */
-           reginfo.ganch = strbeg;
-            DEBUG_GPOS_r(PerlIO_printf(Perl_debug_log,
-                "GPOS: reginfo.ganch = strbeg\n"));
-       }
+        /* note initial PL_regmatch_state position; at end of match we'll
+         * pop back to there and free any higher slabs */
+
+        reginfo->info_aux->old_regmatch_state = old_regmatch_state;
+        reginfo->info_aux->old_regmatch_slab  = old_regmatch_slab;
+        reginfo->info_aux->poscache = NULL;
+
+        SAVEDESTRUCTOR_X(S_cleanup_regmatch_info_aux, reginfo->info_aux);
+
+        if ((prog->extflags & RXf_EVAL_SEEN))
+            S_setup_eval_state(aTHX_ reginfo);
+        else
+            reginfo->info_aux_eval = reginfo->info_aux->info_aux_eval = NULL;
     }
+
+    /* If there is a "must appear" string, look for it. */
+
     if (PL_curpm && (PM_GETRE(PL_curpm) == rx)) {
         /* We have to be careful. If the previous successful match
            was from this regex we don't want a subsequent partially
            successful match to clobber the old results.
            So when we detect this possibility we add a swap buffer
-           to the re, and switch the buffer each match. If we fail
-           we switch it back, otherwise we leave it swapped.
+           to the re, and switch the buffer each match. If we fail,
+           we switch it back; otherwise we leave it swapped.
         */
         swap = prog->offs;
         /* do we need a save destructor here for eval dies? */
@@ -2172,24 +2460,11 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
            PTR2UV(prog->offs)
        ));
     }
-    if (!(flags & REXEC_CHECKED) && (prog->check_substr != NULL || prog->check_utf8 != NULL)) {
-       re_scream_pos_data d;
-
-       d.scream_olds = &scream_olds;
-       d.scream_pos = &scream_pos;
-       s = re_intuit_start(rx, sv, s, strend, flags, &d);
-       if (!s) {
-           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Not present...\n"));
-           goto phooey;        /* not present */
-       }
-    }
-
-
 
     /* Simplest case:  anchored match need be tried only once. */
     /*  [unless only anchor is BOL and multiline is set] */
     if (prog->extflags & (RXf_ANCH & ~RXf_ANCH_GPOS)) {
-       if (s == startpos && regtry(&reginfo, &startpos))
+       if (s == startpos && regtry(reginfo, &s))
            goto got_it;
        else if (multiline || (prog->intflags & PREGf_IMPLICIT)
                 || (prog->extflags & RXf_ANCH_MBOL)) /* XXXX SBOL? */
@@ -2207,7 +2482,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
                     if (s == startpos)
                         goto after_try_utf8;
                     while (1) {
-                        if (regtry(&reginfo, &s)) {
+                        if (regtry(reginfo, &s)) {
                             goto got_it;
                         }
                       after_try_utf8:
@@ -2215,7 +2490,8 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
                             goto phooey;
                         }
                         if (prog->extflags & RXf_USE_INTUIT) {
-                            s = re_intuit_start(rx, sv, s + UTF8SKIP(s), strend, flags, NULL);
+                            s = re_intuit_start(rx, sv, strbeg,
+                                    s + UTF8SKIP(s), strend, flags, NULL);
                             if (!s) {
                                 goto phooey;
                             }
@@ -2230,7 +2506,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
                         goto after_try_latin;
                     }
                     while (1) {
-                        if (regtry(&reginfo, &s)) {
+                        if (regtry(reginfo, &s)) {
                             goto got_it;
                         }
                       after_try_latin:
@@ -2238,7 +2514,8 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
                             goto phooey;
                         }
                         if (prog->extflags & RXf_USE_INTUIT) {
-                            s = re_intuit_start(rx, sv, s + 1, strend, flags, NULL);
+                            s = re_intuit_start(rx, sv, strbeg,
+                                        s + 1, strend, flags, NULL);
                             if (!s) {
                                 goto phooey;
                             }
@@ -2257,7 +2534,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
                /* We can use a more efficient search as newlines are the same in unicode as they are in latin */
                while (s <= end) { /* note it could be possible to match at the end of the string */
                    if (*s++ == '\n') { /* don't need PL_utf8skip here */
-                       if (regtry(&reginfo, &s))
+                       if (regtry(reginfo, &s))
                            goto got_it;
                    }
                }
@@ -2266,12 +2543,11 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
        goto phooey;
     } else if (RXf_GPOS_CHECK == (prog->extflags & RXf_GPOS_CHECK)) 
     {
-        /* the warning about reginfo.ganch being used without initialization
-           is bogus -- we set it above, when prog->extflags & RXf_GPOS_SEEN 
-           and we only enter this block when the same bit is set. */
-        char *tmp_s = reginfo.ganch - prog->gofs;
-
-       if (tmp_s >= strbeg && regtry(&reginfo, &tmp_s))
+        /* For anchored \G, the only position it can match from is
+         * (ganch-gofs); we already set startpos to this above; if intuit
+         * moved us on from there, we can't possibly succeed */
+        assert(startpos == reginfo->ganch - prog->gofs);
+       if (s == startpos && regtry(reginfo, &s))
            goto got_it;
        goto phooey;
     }
@@ -2279,7 +2555,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
     /* Messy cases:  unanchored match. */
     if ((prog->anchored_substr || prog->anchored_utf8) && prog->intflags & PREGf_SKIP) {
        /* we have /x+whatever/ */
-       /* it must be a one character string (XXXX Except UTF_PATTERN?) */
+       /* it must be a one character string (XXXX Except is_utf8_pat?) */
        char ch;
 #ifdef DEBUGGING
        int did_match = 0;
@@ -2292,7 +2568,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
            REXEC_FBC_SCAN(
                if (*s == ch) {
                    DEBUG_EXECUTE_r( did_match = 1 );
-                   if (regtry(&reginfo, &s)) goto got_it;
+                   if (regtry(reginfo, &s)) goto got_it;
                    s += UTF8SKIP(s);
                    while (s < strend && *s == ch)
                        s += UTF8SKIP(s);
@@ -2310,7 +2586,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
            REXEC_FBC_SCAN(
                if (*s == ch) {
                    DEBUG_EXECUTE_r( did_match = 1 );
-                   if (regtry(&reginfo, &s)) goto got_it;
+                   if (regtry(reginfo, &s)) goto got_it;
                    s++;
                    while (s < strend && *s == ch)
                        s++;
@@ -2376,14 +2652,13 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
                  -(I32)(CHR_SVLEN(must)
                         - (SvTAIL(must) != 0) + back_min), strbeg);
         }
-       if (s > PL_bostr)
+       if (s > reginfo->strbeg)
            last1 = HOPc(s, -1);
        else
            last1 = s - 1;      /* bogus */
 
        /* XXXX check_substr already used to find "s", can optimize if
           check_substr==must. */
-       scream_pos = -1;
        dontbother = end_shift;
        strend = HOPc(strend, -dontbother);
        while ( (s <= last) &&
@@ -2396,14 +2671,15 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
                s = HOPc(s, -back_max);
            }
            else {
-               char * const t = (last1 >= PL_bostr) ? HOPc(last1, 1) : last1 + 1;
+               char * const t = (last1 >= reginfo->strbeg)
+                                    ? HOPc(last1, 1) : last1 + 1;
 
                last1 = HOPc(s, -back_min);
                s = t;
            }
            if (utf8_target) {
                while (s <= last1) {
-                   if (regtry(&reginfo, &s))
+                   if (regtry(reginfo, &s))
                        goto got_it;
                     if (s >= last1) {
                         s++; /* to break out of outer loop */
@@ -2414,7 +2690,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
            }
            else {
                while (s <= last1) {
-                   if (regtry(&reginfo, &s))
+                   if (regtry(reginfo, &s))
                        goto got_it;
                    s++;
                }
@@ -2449,7 +2725,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
                     quoted, (int)(strend - s));
            }
        });
-        if (find_byclass(prog, c, s, strend, &reginfo))
+        if (find_byclass(prog, c, s, strend, reginfo))
            goto got_it;
        DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Contradicts stclass... [regexec_flags]\n"));
     }
@@ -2557,7 +2833,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
        /* We don't know much -- general case. */
        if (utf8_target) {
            for (;;) {
-               if (regtry(&reginfo, &s))
+               if (regtry(reginfo, &s))
                    goto got_it;
                if (s >= strend)
                    break;
@@ -2566,7 +2842,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
        }
        else {
            do {
-               if (regtry(&reginfo, &s))
+               if (regtry(reginfo, &s))
                    goto got_it;
            } while (s++ < strend);
        }
@@ -2576,6 +2852,18 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
     goto phooey;
 
 got_it:
+    /* s/// doesn't like it if $& is earlier than where we asked it to
+     * start searching (which can happen on something like /.\G/) */
+    if (       (flags & REXEC_FAIL_ON_UNDERFLOW)
+            && (prog->offs[0].start < stringarg - strbeg))
+    {
+        /* this should only be possible under \G */
+        assert(prog->extflags & RXf_GPOS_SEEN);
+        DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+            "matched, but failing for REXEC_FAIL_ON_UNDERFLOW\n"));
+        goto phooey;
+    }
+
     DEBUG_BUFFERS_r(
        if (swap)
            PerlIO_printf(Perl_debug_log,
@@ -2585,137 +2873,36 @@ got_it:
            );
     );
     Safefree(swap);
-    RX_MATCH_TAINTED_set(rx, PL_reg_flags & RF_tainted);
 
-    if (PL_reg_state.re_state_eval_setup_done)
-       restore_pos(aTHX_ prog);
-    if (RXp_PAREN_NAMES(prog)) 
-        (void)hv_iterinit(RXp_PAREN_NAMES(prog));
+    /* clean up; this will trigger destructors that will free all slabs
+     * above the current one, and cleanup the regmatch_info_aux
+     * and regmatch_info_aux_eval sructs */
 
-    /* make sure $`, $&, $', and $digit will work later */
-    if ( !(flags & REXEC_NOT_FIRST) ) {
-       if (flags & REXEC_COPY_STR) {
-#ifdef PERL_ANY_COW
-           if (SvCANCOW(sv)) {
-               if (DEBUG_C_TEST) {
-                   PerlIO_printf(Perl_debug_log,
-                                 "Copy on write: regexp capture, type %d\n",
-                                 (int) SvTYPE(sv));
-               }
-                RX_MATCH_COPY_FREE(rx);
-               prog->saved_copy = sv_setsv_cow(prog->saved_copy, sv);
-               prog->subbeg = (char *)SvPVX_const(prog->saved_copy);
-               assert (SvPOKp(prog->saved_copy));
-                prog->sublen  = PL_regeol - strbeg;
-                prog->suboffset = 0;
-                prog->subcoffset = 0;
-           } else
-#endif
-           {
-                I32 min = 0;
-                I32 max = PL_regeol - strbeg;
-                I32 sublen;
-
-                if (    (flags & REXEC_COPY_SKIP_POST)
-                    && !(RX_EXTFLAGS(rx) & RXf_PMf_KEEPCOPY) /* //p */
-                    && !(PL_sawampersand & SAWAMPERSAND_RIGHT)
-                ) { /* don't copy $' part of string */
-                    U32 n = 0;
-                    max = -1;
-                    /* calculate the right-most part of the string covered
-                     * by a capture. Due to look-ahead, this may be to
-                     * the right of $&, so we have to scan all captures */
-                    while (n <= prog->lastparen) {
-                        if (prog->offs[n].end > max)
-                            max = prog->offs[n].end;
-                        n++;
-                    }
-                    if (max == -1)
-                        max = (PL_sawampersand & SAWAMPERSAND_LEFT)
-                                ? prog->offs[0].start
-                                : 0;
-                    assert(max >= 0 && max <= PL_regeol - strbeg);
-                }
-
-                if (    (flags & REXEC_COPY_SKIP_PRE)
-                    && !(RX_EXTFLAGS(rx) & RXf_PMf_KEEPCOPY) /* //p */
-                    && !(PL_sawampersand & SAWAMPERSAND_LEFT)
-                ) { /* don't copy $` part of string */
-                    U32 n = 0;
-                    min = max;
-                    /* calculate the left-most part of the string covered
-                     * by a capture. Due to look-behind, this may be to
-                     * the left of $&, so we have to scan all captures */
-                    while (min && n <= prog->lastparen) {
-                        if (   prog->offs[n].start != -1
-                            && prog->offs[n].start < min)
-                        {
-                            min = prog->offs[n].start;
-                        }
-                        n++;
-                    }
-                    if ((PL_sawampersand & SAWAMPERSAND_RIGHT)
-                        && min >  prog->offs[0].end
-                    )
-                        min = prog->offs[0].end;
+    LEAVE_SCOPE(oldsave);
 
-                }
+    if (RXp_PAREN_NAMES(prog)) 
+        (void)hv_iterinit(RXp_PAREN_NAMES(prog));
 
-                assert(min >= 0 && min <= max && min <= PL_regeol - strbeg);
-                sublen = max - min;
+    RX_MATCH_UTF8_set(rx, utf8_target);
 
-                if (RX_MATCH_COPIED(rx)) {
-                    if (sublen > prog->sublen)
-                        prog->subbeg =
-                                (char*)saferealloc(prog->subbeg, sublen+1);
-                }
-                else
-                    prog->subbeg = (char*)safemalloc(sublen+1);
-                Copy(strbeg + min, prog->subbeg, sublen, char);
-                prog->subbeg[sublen] = '\0';
-                prog->suboffset = min;
-                prog->sublen = sublen;
-                RX_MATCH_COPIED_on(rx);
-           }
-            prog->subcoffset = prog->suboffset;
-            if (prog->suboffset && utf8_target) {
-                /* Convert byte offset to chars.
-                 * XXX ideally should only compute this if @-/@+
-                 * has been seen, a la PL_sawampersand ??? */
-
-                /* If there's a direct correspondence between the
-                 * string which we're matching and the original SV,
-                 * then we can use the utf8 len cache associated with
-                 * the SV. In particular, it means that under //g,
-                 * sv_pos_b2u() will use the previously cached
-                 * position to speed up working out the new length of
-                 * subcoffset, rather than counting from the start of
-                 * the string each time. This stops
-                 *   $x = "\x{100}" x 1E6; 1 while $x =~ /(.)/g;
-                 * from going quadratic */
-                if (SvPOKp(sv) && SvPVX(sv) == strbeg)
-                    sv_pos_b2u(sv, &(prog->subcoffset));
-                else
-                    prog->subcoffset = utf8_length((U8*)strbeg,
-                                        (U8*)(strbeg+prog->suboffset));
-            }
-       }
-       else {
-            RX_MATCH_COPY_FREE(rx);
-           prog->subbeg = strbeg;
-           prog->suboffset = 0;
-           prog->subcoffset = 0;
-           prog->sublen = PL_regeol - strbeg;  /* strend may have been modified */
-       }
-    }
+    /* make sure $`, $&, $', and $digit will work later */
+    if ( !(flags & REXEC_NOT_FIRST) )
+        S_reg_set_capture_string(aTHX_ rx,
+                                    strbeg, reginfo->strend,
+                                    sv, flags, utf8_target);
 
     return 1;
 
 phooey:
     DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%sMatch failed%s\n",
                          PL_colors[4], PL_colors[5]));
-    if (PL_reg_state.re_state_eval_setup_done)
-       restore_pos(aTHX_ prog);
+
+    /* clean up; this will trigger destructors that will free all slabs
+     * above the current one, and cleanup the regmatch_info_aux
+     * and regmatch_info_aux_eval sructs */
+
+    LEAVE_SCOPE(oldsave);
+
     if (swap) {
         /* we failed :-( roll it back */
        DEBUG_BUFFERS_r(PerlIO_printf(Perl_debug_log,
@@ -2731,10 +2918,10 @@ phooey:
 }
 
 
-/* Set which rex is pointed to by PL_reg_state, handling ref counting.
+/* Set which rex is pointed to by PL_reg_curpm, handling ref counting.
  * Do inc before dec, in case old and new rex are the same */
 #define SET_reg_curpm(Re2) \
-    if (PL_reg_state.re_state_eval_setup_done) {    \
+    if (reginfo->info_aux_eval) {                   \
        (void)ReREFCNT_inc(Re2);                    \
        ReREFCNT_dec(PM_GETRE(PL_reg_curpm));       \
        PM_SETRE((PL_reg_curpm), (Re2));            \
@@ -2759,74 +2946,7 @@ S_regtry(pTHX_ regmatch_info *reginfo, char **startposp)
 
     reginfo->cutpoint=NULL;
 
-    if ((prog->extflags & RXf_EVAL_SEEN)
-       && !PL_reg_state.re_state_eval_setup_done)
-    {
-       MAGIC *mg;
-
-       PL_reg_state.re_state_eval_setup_done = TRUE;
-       if (reginfo->sv) {
-           /* Make $_ available to executed code. */
-           if (reginfo->sv != DEFSV) {
-               SAVE_DEFSV;
-               DEFSV_set(reginfo->sv);
-           }
-       
-           if (!(SvTYPE(reginfo->sv) >= SVt_PVMG && SvMAGIC(reginfo->sv)
-                 && (mg = mg_find(reginfo->sv, PERL_MAGIC_regex_global)))) {
-               /* prepare for quick setting of pos */
-#ifdef PERL_OLD_COPY_ON_WRITE
-               if (SvIsCOW(reginfo->sv))
-                   sv_force_normal_flags(reginfo->sv, 0);
-#endif
-               mg = sv_magicext(reginfo->sv, NULL, PERL_MAGIC_regex_global,
-                                &PL_vtbl_mglob, NULL, 0);
-               mg->mg_len = -1;
-           }
-           PL_reg_magic    = mg;
-           PL_reg_oldpos   = mg->mg_len;
-           SAVEDESTRUCTOR_X(restore_pos, prog);
-        }
-        if (!PL_reg_curpm) {
-           Newxz(PL_reg_curpm, 1, PMOP);
-#ifdef USE_ITHREADS
-            {
-               SV* const repointer = &PL_sv_undef;
-                /* this regexp is also owned by the new PL_reg_curpm, which
-                  will try to free it.  */
-                av_push(PL_regex_padav, repointer);
-                PL_reg_curpm->op_pmoffset = av_len(PL_regex_padav);
-                PL_regex_pad = AvARRAY(PL_regex_padav);
-            }
-#endif      
-        }
-       SET_reg_curpm(rx);
-       PL_reg_oldcurpm = PL_curpm;
-       PL_curpm = PL_reg_curpm;
-       if (RXp_MATCH_COPIED(prog)) {
-           /*  Here is a serious problem: we cannot rewrite subbeg,
-               since it may be needed if this match fails.  Thus
-               $` inside (?{}) could fail... */
-           PL_reg_oldsaved = prog->subbeg;
-           PL_reg_oldsavedlen = prog->sublen;
-           PL_reg_oldsavedoffset = prog->suboffset;
-           PL_reg_oldsavedcoffset = prog->suboffset;
-#ifdef PERL_ANY_COW
-           PL_nrs = prog->saved_copy;
-#endif
-           RXp_MATCH_COPIED_off(prog);
-       }
-       else
-           PL_reg_oldsaved = NULL;
-       prog->subbeg = PL_bostr;
-       prog->suboffset = 0;
-       prog->subcoffset = 0;
-       prog->sublen = PL_regeol - PL_bostr; /* strend may have been modified */
-    }
-#ifdef DEBUGGING
-    PL_reg_starttry = *startposp;
-#endif
-    prog->offs[0].start = *startposp - PL_bostr;
+    prog->offs[0].start = *startposp - reginfo->strbeg;
     prog->lastparen = 0;
     prog->lastcloseparen = 0;
 
@@ -2875,7 +2995,7 @@ S_regtry(pTHX_ regmatch_info *reginfo, char **startposp)
    "unreachable code" warnings, which are bogus, but distracting. */
 #define CACHEsayNO \
     if (ST.cache_mask) \
-       PL_reg_poscache[ST.cache_offset] |= ST.cache_mask; \
+       reginfo->info_aux->poscache[ST.cache_offset] |= ST.cache_mask; \
     sayNO
 
 /* this is used to determine how far from the left messages like
@@ -2890,9 +3010,6 @@ S_regtry(pTHX_ regmatch_info *reginfo, char **startposp)
 #define CHRTEST_NOT_A_CP_1 -999
 #define CHRTEST_NOT_A_CP_2 -998
 
-#define SLAB_FIRST(s) (&(s)->states[0])
-#define SLAB_LAST(s)  (&(s)->states[PERL_REGMATCH_SLAB_SLOTS-1])
-
 /* grab a new slab and return the first slot in it */
 
 STATIC regmatch_state *
@@ -3208,25 +3325,9 @@ S_reg_check_named_buff_matched(pTHX_ const regexp *rex, const regnode *scan)
 }
 
 
-/* free all slabs above current one  - called during LEAVE_SCOPE */
-
-STATIC void
-S_clear_backtrack_stack(pTHX_ void *p)
-{
-    regmatch_slab *s = PL_regmatch_slab->next;
-    PERL_UNUSED_ARG(p);
-
-    if (!s)
-       return;
-    PL_regmatch_slab->next = NULL;
-    while (s) {
-       regmatch_slab * const osl = s;
-       s = s->next;
-       Safefree(osl);
-    }
-}
 static bool
-S_setup_EXACTISH_ST_c1_c2(pTHX_ const regnode * const text_node, int *c1p, U8* c1_utf8, int *c2p, U8* c2_utf8)
+S_setup_EXACTISH_ST_c1_c2(pTHX_ const regnode * const text_node, int *c1p,
+        U8* c1_utf8, int *c2p, U8* c2_utf8, regmatch_info *reginfo)
 {
     /* This function determines if there are one or two characters that match
      * the first character of the passed-in EXACTish node <text_node>, and if
@@ -3278,11 +3379,12 @@ S_setup_EXACTISH_ST_c1_c2(pTHX_ const regnode * const text_node, int *c1p, U8* c
      * point (unless inappropriately coerced to unsigned).   *<c1p> will equal
      * *<c2p> if and only if <c1_utf8> and <c2_utf8> are the same. */
 
-    const bool utf8_target = PL_reg_match_utf8;
+    const bool utf8_target = reginfo->is_utf8_target;
 
     UV c1 = CHRTEST_NOT_A_CP_1;
     UV c2 = CHRTEST_NOT_A_CP_2;
     bool use_chrtest_void = FALSE;
+    const bool is_utf8_pat = reginfo->is_utf8_pat;
 
     /* Used when we have both utf8 input and utf8 output, to avoid converting
      * to/from code points */
@@ -3298,7 +3400,7 @@ S_setup_EXACTISH_ST_c1_c2(pTHX_ const regnode * const text_node, int *c1p, U8* c
          * character.  If both the pat and the target are UTF-8, we can just
          * copy the input to the output, avoiding finding the code point of
          * that character */
-        if (! UTF_PATTERN) {
+        if (!is_utf8_pat) {
             c2 = c1 = *pat;
         }
         else if (utf8_target) {
@@ -3311,10 +3413,10 @@ S_setup_EXACTISH_ST_c1_c2(pTHX_ const regnode * const text_node, int *c1p, U8* c
         }
     }
     else /* an EXACTFish node */
-         if ((UTF_PATTERN
+         if ((is_utf8_pat
                     && is_MULTI_CHAR_FOLD_utf8_safe(pat,
                                                     pat + STR_LEN(text_node)))
-             || (! UTF_PATTERN
+             || (!is_utf8_pat
                     && is_MULTI_CHAR_FOLD_latin1_safe(pat,
                                                     pat + STR_LEN(text_node))))
     {
@@ -3324,7 +3426,7 @@ S_setup_EXACTISH_ST_c1_c2(pTHX_ const regnode * const text_node, int *c1p, U8* c
         use_chrtest_void = TRUE;
     }
     else { /* an EXACTFish node which doesn't begin with a multi-char fold */
-        c1 = (UTF_PATTERN) ? valid_utf8_to_uvchr(pat, NULL) : *pat;
+        c1 = is_utf8_pat ? valid_utf8_to_uvchr(pat, NULL) : *pat;
         if (c1 > 256) {
             /* Load the folds hash, if not already done */
             SV** listp;
@@ -3488,12 +3590,11 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
     dMY_CXT;
 #endif
     dVAR;
-    const bool utf8_target = PL_reg_match_utf8;
+    const bool utf8_target = reginfo->is_utf8_target;
     const U32 uniflags = UTF8_ALLOW_DEFAULT;
     REGEXP *rex_sv = reginfo->prog;
     regexp *rex = ReANY(rex_sv);
     RXi_GET_DECL(rex,rexi);
-    I32        oldsave;
     /* the current state. This is a cached copy of PL_regmatch_state */
     regmatch_state *st;
     /* cache heavy used fields of st in registers */
@@ -3552,6 +3653,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
     U32 maxopenparen = 0;       /* max '(' index seen so far */
     int to_complement;  /* Invert the result? */
     _char_class_number classnum;
+    bool is_utf8_pat = reginfo->is_utf8_pat;
 
 #ifdef DEBUGGING
     GET_RE_DEBUG_FLAGS_DECL;
@@ -3570,23 +3672,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
     DEBUG_OPTIMISE_r( DEBUG_EXECUTE_r({
            PerlIO_printf(Perl_debug_log,"regmatch start\n");
     }));
-    /* on first ever call to regmatch, allocate first slab */
-    if (!PL_regmatch_slab) {
-       Newx(PL_regmatch_slab, 1, regmatch_slab);
-       PL_regmatch_slab->prev = NULL;
-       PL_regmatch_slab->next = NULL;
-       PL_regmatch_state = SLAB_FIRST(PL_regmatch_slab);
-    }
 
-    oldsave = PL_savestack_ix;
-    SAVEDESTRUCTOR_X(S_clear_backtrack_stack, NULL);
-    SAVEVPTR(PL_regmatch_slab);
-    SAVEVPTR(PL_regmatch_state);
-
-    /* grab next free state slot */
-    st = ++PL_regmatch_state;
-    if (st >  SLAB_LAST(PL_regmatch_slab))
-       st = PL_regmatch_state = S_push_slab(aTHX);
+    st = PL_regmatch_state;
 
     /* Note that nextchr is a byte even in UTF */
     SET_nextchr;
@@ -3620,15 +3707,12 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
 
        switch (state_num) {
        case BOL: /*  /^../  */
-           if (locinput == PL_bostr)
-           {
-               /* reginfo->till = reginfo->bol; */
+           if (locinput == reginfo->strbeg)
                break;
-           }
            sayNO;
 
        case MBOL: /*  /^../m  */
-           if (locinput == PL_bostr ||
+           if (locinput == reginfo->strbeg ||
                (!NEXTCHR_IS_EOS && locinput[-1] == '\n'))
            {
                break;
@@ -3636,7 +3720,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
            sayNO;
 
        case SBOL: /*  /^../s  */
-           if (locinput == PL_bostr)
+           if (locinput == reginfo->strbeg)
                break;
            sayNO;
 
@@ -3648,7 +3732,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
        case KEEPS: /*   \K  */
            /* update the startpoint */
            st->u.keeper.val = rex->offs[0].start;
-           rex->offs[0].start = locinput - PL_bostr;
+           rex->offs[0].start = locinput - reginfo->strbeg;
            PUSH_STATE_GOTO(KEEPS_next, next, locinput);
            assert(0); /*NOTREACHED*/
        case KEEPS_next_fail:
@@ -3669,7 +3753,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
          seol:
            if (!NEXTCHR_IS_EOS && nextchr != '\n')
                sayNO;
-           if (PL_regeol - locinput > 1)
+           if (reginfo->strend - locinput > 1)
                sayNO;
            break;
 
@@ -3807,7 +3891,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                   shortest accept state and the wordnum of the longest
                   accept state */
 
-               while ( state && uc <= (U8*)PL_regeol ) {
+               while ( state && uc <= (U8*)(reginfo->strend) ) {
                     U32 base = trie->states[ state ].trans.base;
                     UV uvc = 0;
                     U16 charid = 0;
@@ -3841,7 +3925,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                    });
 
                    /* read a char and goto next state */
-                   if ( base && (foldlen || uc < (U8*)PL_regeol)) {
+                   if ( base && (foldlen || uc < (U8*)(reginfo->strend))) {
                        I32 offset;
                        REXEC_TRIE_READ_CHAR(trie_type, trie, widecharmap, uc,
                                             uscan, len, uvc, charid, foldlen,
@@ -4040,7 +4124,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
        case EXACT: {            /*  /abc/        */
            char *s = STRING(scan);
            ln = STR_LEN(scan);
-           if (utf8_target != UTF_PATTERN) {
+           if (utf8_target != is_utf8_pat) {
                /* The target and the pattern have differing utf8ness. */
                char *l = locinput;
                const char * const e = s + ln;
@@ -4056,9 +4140,9 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                      * is an invariant, but there are tests in the test suite
                      * dealing with (??{...}) which violate this) */
                    while (s < e) {
-                       if (l >= PL_regeol)
-                            sayNO;
-                        if (UTF8_IS_ABOVE_LATIN1(* (U8*) l)) {
+                       if (l >= reginfo->strend
+                            || UTF8_IS_ABOVE_LATIN1(* (U8*) l))
+                        {
                             sayNO;
                         }
                         if (UTF8_IS_INVARIANT(*(U8*)l)) {
@@ -4079,7 +4163,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                else {
                    /* The target is not utf8, the pattern is utf8. */
                    while (s < e) {
-                        if (l >= PL_regeol || UTF8_IS_ABOVE_LATIN1(* (U8*) s))
+                        if (l >= reginfo->strend
+                            || UTF8_IS_ABOVE_LATIN1(* (U8*) s))
                         {
                             sayNO;
                         }
@@ -4099,17 +4184,18 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                    }
                }
                locinput = l;
-               break;
            }
-           /* The target and the pattern have the same utf8ness. */
-           /* Inline the first character, for speed. */
-           if (UCHARAT(s) != nextchr)
-               sayNO;
-           if (PL_regeol - locinput < ln)
-               sayNO;
-           if (ln > 1 && memNE(s, locinput, ln))
-               sayNO;
-           locinput += ln;
+            else {
+                /* The target and the pattern have the same utf8ness. */
+                /* Inline the first character, for speed. */
+                if (reginfo->strend - locinput < ln
+                    || UCHARAT(s) != nextchr
+                    || (ln > 1 && memNE(s, locinput, ln)))
+                {
+                    sayNO;
+                }
+                locinput += ln;
+            }
            break;
            }
 
@@ -4119,7 +4205,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
            const char * s;
            U32 fold_utf8_flags;
 
-           PL_reg_flags |= RF_tainted;
+            RX_MATCH_TAINTED_on(reginfo->prog);
             folder = foldEQ_locale;
             fold_array = PL_fold_locale;
            fold_utf8_flags = FOLDEQ_UTF8_LOCALE;
@@ -4130,7 +4216,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
        case EXACTFU:            /*  /abc/iu      */
            folder = foldEQ_latin1;
            fold_array = PL_fold_latin1;
-           fold_utf8_flags = (UTF_PATTERN) ? FOLDEQ_S1_ALREADY_FOLDED : 0;
+           fold_utf8_flags = is_utf8_pat ? FOLDEQ_S1_ALREADY_FOLDED : 0;
            goto do_exactf;
 
        case EXACTFA:            /*  /abc/iaa     */
@@ -4148,13 +4234,13 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
            s = STRING(scan);
            ln = STR_LEN(scan);
 
-           if (utf8_target || UTF_PATTERN || state_num == EXACTFU_SS) {
+           if (utf8_target || is_utf8_pat || state_num == EXACTFU_SS) {
              /* Either target or the pattern are utf8, or has the issue where
               * the fold lengths may differ. */
                const char * const l = locinput;
-               char *e = PL_regeol;
+               char *e = reginfo->strend;
 
-               if (! foldEQ_utf8_flags(s, 0,  ln, cBOOL(UTF_PATTERN),
+               if (! foldEQ_utf8_flags(s, 0,  ln, is_utf8_pat,
                                        l, &e, 0,  utf8_target, fold_utf8_flags))
                {
                    sayNO;
@@ -4170,7 +4256,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
            {
                sayNO;
            }
-           if (PL_regeol - locinput < ln)
+           if (reginfo->strend - locinput < ln)
                sayNO;
            if (ln > 1 && ! folder(s, locinput, ln))
                sayNO;
@@ -4183,7 +4269,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
         * have to set the FLAGS fields of these */
        case BOUNDL:  /*  /\b/l  */
        case NBOUNDL: /*  /\B/l  */
-           PL_reg_flags |= RF_tainted;
+            RX_MATCH_TAINTED_on(reginfo->prog);
            /* FALL THROUGH */
        case BOUND:   /*  /\b/   */
        case BOUNDU:  /*  /\b/u  */
@@ -4196,26 +4282,27 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                && FLAGS(scan) != REGEX_ASCII_RESTRICTED_CHARSET
                && FLAGS(scan) != REGEX_ASCII_MORE_RESTRICTED_CHARSET)
            {
-               if (locinput == PL_bostr)
+               if (locinput == reginfo->strbeg)
                    ln = '\n';
                else {
-                   const U8 * const r = reghop3((U8*)locinput, -1, (U8*)PL_bostr);
+                   const U8 * const r =
+                            reghop3((U8*)locinput, -1, (U8*)(reginfo->strbeg));
 
                    ln = utf8n_to_uvchr(r, UTF8SKIP(r), 0, uniflags);
                }
                if (FLAGS(scan) != REGEX_LOCALE_CHARSET) {
-                   ln = isALNUM_uni(ln);
+                   ln = isWORDCHAR_uni(ln);
                     if (NEXTCHR_IS_EOS)
                         n = 0;
                     else {
                         LOAD_UTF8_CHARCLASS_ALNUM();
-                        n = swash_fetch(PL_utf8_alnum, (U8*)locinput,
+                        n = swash_fetch(PL_utf8_swash_ptrs[_CC_WORDCHAR], (U8*)locinput,
                                                                 utf8_target);
                     }
                }
                else {
-                   ln = isALNUM_LC_uvchr(UNI_TO_NATIVE(ln));
-                   n = NEXTCHR_IS_EOS ? 0 : isALNUM_LC_utf8((U8*)locinput);
+                   ln = isWORDCHAR_LC_uvchr(UNI_TO_NATIVE(ln));
+                   n = NEXTCHR_IS_EOS ? 0 : isWORDCHAR_LC_utf8((U8*)locinput);
                }
            }
            else {
@@ -4231,7 +4318,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                 *      byte is never mistakable for ASCII, and so the test
                 *      will say it is not a word character, which is the
                 *      correct answer. */
-               ln = (locinput != PL_bostr) ?
+               ln = (locinput != reginfo->strbeg) ?
                    UCHARAT(locinput - 1) : '\n';
                switch (FLAGS(scan)) {
                    case REGEX_UNICODE_CHARSET:
@@ -4239,12 +4326,12 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                        n = NEXTCHR_IS_EOS ? 0 : isWORDCHAR_L1(nextchr);
                        break;
                    case REGEX_LOCALE_CHARSET:
-                       ln = isALNUM_LC(ln);
-                       n = NEXTCHR_IS_EOS ? 0 : isALNUM_LC(nextchr);
+                       ln = isWORDCHAR_LC(ln);
+                       n = NEXTCHR_IS_EOS ? 0 : isWORDCHAR_LC(nextchr);
                        break;
                    case REGEX_DEPENDS_CHARSET:
-                       ln = isALNUM(ln);
-                       n = NEXTCHR_IS_EOS ? 0 : isALNUM(nextchr);
+                       ln = isWORDCHAR(ln);
+                       n = NEXTCHR_IS_EOS ? 0 : isWORDCHAR(nextchr);
                        break;
                    case REGEX_ASCII_RESTRICTED_CHARSET:
                    case REGEX_ASCII_MORE_RESTRICTED_CHARSET:
@@ -4263,19 +4350,18 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
            break;
 
        case ANYOF:  /*  /[abc]/       */
+       case ANYOF_WARN_SUPER:
             if (NEXTCHR_IS_EOS)
                 sayNO;
            if (utf8_target) {
                if (!reginclass(rex, scan, (U8*)locinput, utf8_target))
                    sayNO;
                locinput += UTF8SKIP(locinput);
-               break;
            }
            else {
                if (!REGINCLASS(rex, scan, (U8*)locinput))
                    sayNO;
                locinput++;
-               break;
            }
            break;
 
@@ -4292,19 +4378,19 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
 
             /* The locale hasn't influenced the outcome before this, so defer
              * tainting until now */
-            PL_reg_flags |= RF_tainted;
+            RX_MATCH_TAINTED_on(reginfo->prog);
 
             /* Use isFOO_lc() for characters within Latin1.  (Note that
              * UTF8_IS_INVARIANT works even on non-UTF-8 strings, or else
              * wouldn't be invariant) */
             if (UTF8_IS_INVARIANT(nextchr) || ! utf8_target) {
-                if (! (to_complement ^ cBOOL(isFOO_lc(FLAGS(scan), nextchr)))) {
+                if (! (to_complement ^ cBOOL(isFOO_lc(FLAGS(scan), (U8) nextchr)))) {
                     sayNO;
                 }
             }
             else if (UTF8_IS_DOWNGRADEABLE_START(nextchr)) {
                 if (! (to_complement ^ cBOOL(isFOO_lc(FLAGS(scan),
-                                        TWO_BYTE_UTF8_TO_UNI(nextchr,
+                                        (U8) TWO_BYTE_UTF8_TO_UNI(nextchr,
                                                             *(locinput + 1))))))
                 {
                     sayNO;
@@ -4501,7 +4587,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                locinput++;         /* Match the . or CR */
                if (nextchr == '\r' /* And if it was CR, and the next is LF,
                                       match the LF */
-                   && locinput < PL_regeol
+                   && locinput < reginfo->strend
                    && UCHARAT(locinput) == '\n')
                 {
                     locinput++;
@@ -4510,8 +4596,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
            else {
 
                /* Utf8: See if is ( CR LF ); already know that locinput <
-                * PL_regeol, so locinput+1 is in bounds */
-               if ( nextchr == '\r' && locinput+1 < PL_regeol
+                * reginfo->strend, so locinput+1 is in bounds */
+               if ( nextchr == '\r' && locinput+1 < reginfo->strend
                      && UCHARAT(locinput + 1) == '\n')
                 {
                    locinput += 2;
@@ -4528,7 +4614,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                    LOAD_UTF8_CHARCLASS_GCB();
 
                     /* Match (prepend)*   */
-                    while (locinput < PL_regeol
+                    while (locinput < reginfo->strend
                            && (len = is_GCB_Prepend_utf8(locinput)))
                     {
                         previous_prepend = locinput;
@@ -4539,7 +4625,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                     * the next thing won't match, back off the last prepend we
                     * matched, as it is guaranteed to match the begin */
                    if (previous_prepend
-                       && (locinput >=  PL_regeol
+                       && (locinput >=  reginfo->strend
                            || (! swash_fetch(PL_utf8_X_regular_begin,
                                             (U8*)locinput, utf8_target)
                                 && ! is_GCB_SPECIAL_BEGIN_START_utf8(locinput)))
@@ -4548,7 +4634,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                        locinput = previous_prepend;
                    }
 
-                   /* Note that here we know PL_regeol > locinput, as we
+                   /* Note that here we know reginfo->strend > locinput, as we
                     * tested that upon input to this switch case, and if we
                     * moved locinput forward, we tested the result just above
                     * and it either passed, or we backed off so that it will
@@ -4571,7 +4657,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                          * RI+ */
                         if ((len = is_GCB_RI_utf8(locinput))) {
                             locinput += len;
-                            while (locinput < PL_regeol
+                            while (locinput < reginfo->strend
                                    && (len = is_GCB_RI_utf8(locinput)))
                             {
                                 locinput += len;
@@ -4579,7 +4665,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                         } else if ((len = is_GCB_T_utf8(locinput))) {
                             /* Another possibility is T+ */
                             locinput += len;
-                            while (locinput < PL_regeol
+                            while (locinput < reginfo->strend
                                 && (len = is_GCB_T_utf8(locinput)))
                             {
                                 locinput += len;
@@ -4592,7 +4678,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                              * L* (L | LVT T* | V * V* T* | LV  V* T*) */
 
                             /* Match L*           */
-                            while (locinput < PL_regeol
+                            while (locinput < reginfo->strend
                                    && (len = is_GCB_L_utf8(locinput)))
                             {
                                 locinput += len;
@@ -4604,7 +4690,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                              * equation, we have a complete hangul syllable.
                              * Are done. */
 
-                            if (locinput < PL_regeol
+                            if (locinput < reginfo->strend
                                 && is_GCB_LV_LVT_V_utf8(locinput))
                             {
                                 /* Otherwise keep going.  Must be LV, LVT or V.
@@ -4622,7 +4708,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                                     /* Must be  V or LV.  Take it, then match
                                      * V*     */
                                     locinput += UTF8SKIP(locinput);
-                                    while (locinput < PL_regeol
+                                    while (locinput < reginfo->strend
                                            && (len = is_GCB_V_utf8(locinput)))
                                     {
                                         locinput += len;
@@ -4631,7 +4717,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
 
                                 /* And any of LV, LVT, or V can be followed
                                  * by T*            */
-                                while (locinput < PL_regeol
+                                while (locinput < reginfo->strend
                                        && (len = is_GCB_T_utf8(locinput)))
                                 {
                                     locinput += len;
@@ -4641,7 +4727,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                     }
 
                     /* Match any extender */
-                    while (locinput < PL_regeol
+                    while (locinput < reginfo->strend
                             && swash_fetch(PL_utf8_X_extend,
                                             (U8*)locinput, utf8_target))
                     {
@@ -4649,7 +4735,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                     }
                }
             exit_utf8:
-               if (locinput > PL_regeol) sayNO;
+               if (locinput > reginfo->strend) sayNO;
            }
            break;
             
@@ -4660,13 +4746,13 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
               op.  */
            /* don't initialize these in the declaration, it makes C++
               unhappy */
-           char *s;
+           const char *s;
            char type;
            re_fold_t folder;
            const U8 *fold_array;
            UV utf8_fold_flags;
 
-           PL_reg_flags |= RF_tainted;
+            RX_MATCH_TAINTED_on(reginfo->prog);
            folder = foldEQ_locale;
            fold_array = PL_fold_locale;
            type = REFFL;
@@ -4711,7 +4797,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
            goto do_nref_ref_common;
 
        case REFFL:  /*  /\1/il  */
-           PL_reg_flags |= RF_tainted;
+            RX_MATCH_TAINTED_on(reginfo->prog);
            folder = foldEQ_locale;
            fold_array = PL_fold_locale;
            utf8_fold_flags = FOLDEQ_UTF8_LOCALE;
@@ -4746,23 +4832,23 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
 
          do_nref_ref_common:
            ln = rex->offs[n].start;
-           PL_reg_leftiter = PL_reg_maxiter;           /* Void cache */
+           reginfo->poscache_iter = reginfo->poscache_maxiter; /* Void cache */
            if (rex->lastparen < n || ln == -1)
                sayNO;                  /* Do not match unless seen CLOSEn. */
            if (ln == rex->offs[n].end)
                break;
 
-           s = PL_bostr + ln;
+           s = reginfo->strbeg + ln;
            if (type != REF     /* REF can do byte comparison */
                && (utf8_target || type == REFFU))
            { /* XXX handle REFFL better */
-               char * limit = PL_regeol;
+               char * limit = reginfo->strend;
 
                /* This call case insensitively compares the entire buffer
                    * at s, with the current input starting at locinput, but
-                   * not going off the end given by PL_regeol, and returns in
-                   * <limit> upon success, how much of the current input was
-                   * matched */
+                    * not going off the end given by reginfo->strend, and
+                    * returns in <limit> upon success, how much of the
+                    * current input was matched */
                if (! foldEQ_utf8_flags(s, NULL, rex->offs[n].end - ln, utf8_target,
                                    locinput, &limit, 0, utf8_target, utf8_fold_flags))
                {
@@ -4779,7 +4865,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                 UCHARAT(s) != fold_array[nextchr]))
                sayNO;
            ln = rex->offs[n].end - ln;
-           if (locinput + ln > PL_regeol)
+           if (locinput + ln > reginfo->strend)
                sayNO;
            if (ln > 1 && (type == REF
                           ? memNE(s, locinput, ln)
@@ -4847,32 +4933,12 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                OP * const oop = PL_op;
                COP * const ocurcop = PL_curcop;
                OP *nop;
-               char *saved_regeol = PL_regeol;
-               struct re_save_state saved_state;
                CV *newcv;
 
                /* save *all* paren positions */
                regcppush(rex, 0, maxopenparen);
                REGCP_SET(runops_cp);
 
-               /* To not corrupt the existing regex state while executing the
-                * eval we would normally put it on the save stack, like with
-                * save_re_context. However, re-evals have a weird scoping so we
-                * can't just add ENTER/LEAVE here. With that, things like
-                *
-                *    (?{$a=2})(a(?{local$a=$a+1}))*aak*c(?{$b=$a})
-                *
-                * would break, as they expect the localisation to be unwound
-                * only when the re-engine backtracks through the bit that
-                * localised it.
-                *
-                * What we do instead is just saving the state in a local c
-                * variable.
-                */
-               Copy(&PL_reg_state, &saved_state, 1, struct re_save_state);
-
-               PL_reg_state.re_reparsing = FALSE;
-
                if (!caller_cv)
                    caller_cv = find_runcv(NULL);
 
@@ -4906,12 +4972,13 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                 * points to newcv's pad. */
                if (newcv != last_pushed_cv || PL_comppad != last_pad)
                {
-                   I32 depth = (newcv == caller_cv) ? 0 : 1;
+                    U8 flags = (CXp_SUB_RE |
+                                ((newcv == caller_cv) ? CXp_SUB_RE_FAKE : 0));
                    if (last_pushed_cv) {
-                       CHANGE_MULTICALL_WITHDEPTH(newcv, depth);
+                       CHANGE_MULTICALL_FLAGS(newcv, flags);
                    }
                    else {
-                       PUSH_MULTICALL_WITHDEPTH(newcv, depth);
+                       PUSH_MULTICALL_FLAGS(newcv, flags);
                    }
                    last_pushed_cv = newcv;
                }
@@ -4958,7 +5025,10 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                DEBUG_STATE_r( PerlIO_printf(Perl_debug_log, 
                    "  re EVAL PL_op=0x%"UVxf"\n", PTR2UV(nop)) );
 
-               rex->offs[0].end = PL_reg_magic->mg_len = locinput - PL_bostr;
+               rex->offs[0].end = locinput - reginfo->strbeg;
+                if (reginfo->info_aux_eval->pos_magic)
+                        reginfo->info_aux_eval->pos_magic->mg_len
+                                        = locinput - reginfo->strbeg;
 
                 if (sv_yes_mark) {
                     SV *sv_mrk = get_sv("REGMARK", 1);
@@ -5017,16 +5087,14 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
 
                }
 
-               Copy(&saved_state, &PL_reg_state, 1, struct re_save_state);
-
                /* *** Note that at this point we don't restore
                 * PL_comppad, (or pop the CxSUB) on the assumption it may
                 * be used again soon. This is safe as long as nothing
                 * in the regexp code uses the pad ! */
                PL_op = oop;
                PL_curcop = ocurcop;
-               PL_regeol = saved_regeol;
                S_regcp_restore(aTHX_ rex, runops_cp, &maxopenparen);
+               PL_curpm = PL_reg_curpm;
 
                if (logical != 2)
                    break;
@@ -5087,8 +5155,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
                 re->subcoffset = rex->subcoffset;
                rei = RXi_GET(re);
                 DEBUG_EXECUTE_r(
-                    debug_start_match(re_sv, utf8_target, locinput, PL_regeol,
-                        "Matching embedded");
+                    debug_start_match(re_sv, utf8_target, locinput,
+                                    reginfo->strend, "Matching embedded");
                );              
                startpoint = rei->program + 1;
                        ST.close_paren = 0; /* only used for GOSUB */
@@ -5105,15 +5173,17 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
 
                maxopenparen = 0;
 
-               /* XXXX This is too dramatic a measure... */
-               PL_reg_maxiter = 0;
+                /* invalidate the S-L poscache. We're now executing a
+                 * different set of WHILEM ops (and their associated
+                 * indexes) against the same string, so the bits in the
+                 * cache are meaningless. Setting maxiter to zero forces
+                 * the cache to be invalidated and zeroed before reuse.
+                * XXX This is too dramatic a measure. Ideally we should
+                 * save the old cache and restore when running the outer
+                 * pattern again */
+               reginfo->poscache_maxiter = 0;
 
-               ST.toggle_reg_flags = PL_reg_flags;
-               if (RX_UTF8(re_sv))
-                   PL_reg_flags |= RF_utf8;
-               else
-                   PL_reg_flags &= ~RF_utf8;
-               ST.toggle_reg_flags ^= PL_reg_flags; /* diff of old and new */
+                is_utf8_pat = reginfo->is_utf8_pat = cBOOL(RX_UTF8(re_sv));
 
                ST.prev_rex = rex_sv;
                ST.prev_curlyx = cur_curlyx;
@@ -5132,8 +5202,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
 
        case EVAL_AB: /* cleanup after a successful (??{A})B */
            /* note: this is called twice; first after popping B, then A */
-           PL_reg_flags ^= ST.toggle_reg_flags; 
            rex_sv = ST.prev_rex;
+            is_utf8_pat = reginfo->is_utf8_pat = cBOOL(RX_UTF8(rex_sv));
            SET_reg_curpm(rex_sv);
            rex = ReANY(rex_sv);
            rexi = RXi_GET(rex);
@@ -5141,8 +5211,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
            cur_eval = ST.prev_eval;
            cur_curlyx = ST.prev_curlyx;
 
-           /* XXXX This is too dramatic a measure... */
-           PL_reg_maxiter = 0;
+           /* Invalidate cache. See "invalidate" comment above. */
+           reginfo->poscache_maxiter = 0;
             if ( nochange_depth )
                nochange_depth--;
            sayYES;
@@ -5150,8 +5220,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
 
        case EVAL_AB_fail: /* unsuccessfully ran A or B in (??{A})B */
            /* note: this is called twice; first after popping B, then A */
-           PL_reg_flags ^= ST.toggle_reg_flags; 
            rex_sv = ST.prev_rex;
+            is_utf8_pat = reginfo->is_utf8_pat = cBOOL(RX_UTF8(rex_sv));
            SET_reg_curpm(rex_sv);
            rex = ReANY(rex_sv);
            rexi = RXi_GET(rex); 
@@ -5160,8 +5230,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
            regcppop(rex, &maxopenparen);
            cur_eval = ST.prev_eval;
            cur_curlyx = ST.prev_curlyx;
-           /* XXXX This is too dramatic a measure... */
-           PL_reg_maxiter = 0;
+           /* Invalidate cache. See "invalidate" comment above. */
+           reginfo->poscache_maxiter = 0;
            if ( nochange_depth )
                nochange_depth--;
            sayNO_SILENT;
@@ -5169,7 +5239,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
 
        case OPEN: /*  (  */
            n = ARG(scan);  /* which paren pair */
-           rex->offs[n].start_tmp = locinput - PL_bostr;
+           rex->offs[n].start_tmp = locinput - reginfo->strbeg;
            if (n > maxopenparen)
                maxopenparen = n;
            DEBUG_BUFFERS_r(PerlIO_printf(Perl_debug_log,
@@ -5186,7 +5256,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
 /* XXX really need to log other places start/end are set too */
 #define CLOSE_CAPTURE \
     rex->offs[n].start = rex->offs[n].start_tmp; \
-    rex->offs[n].end = locinput - PL_bostr; \
+    rex->offs[n].end = locinput - reginfo->strbeg; \
     DEBUG_BUFFERS_r(PerlIO_printf(Perl_debug_log, \
        "rex=0x%"UVxf" offs=0x%"UVxf": \\%"UVuf": set %"IVdf"..%"IVdf"\n", \
        PTR2UV(rex), \
@@ -5251,7 +5321,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
             break;
 
        case IFTHEN:   /*  (?(cond)A|B)  */
-           PL_reg_leftiter = PL_reg_maxiter;           /* Void cache */
+           reginfo->poscache_iter = reginfo->poscache_maxiter; /* Void cache */
            if (sw)
                next = NEXTOPER(NEXTOPER(scan));
            else {
@@ -5439,33 +5509,66 @@ NULL
                goto do_whilem_B_max;
            }
 
-           /* super-linear cache processing */
+           /* super-linear cache processing.
+             *
+             * The idea here is that for certain types of CURLYX/WHILEM -
+             * principally those whose upper bound is infinity (and
+             * excluding regexes that have things like \1 and other very
+             * non-regular expresssiony things), then if a pattern like
+             * /....A*.../ fails and we backtrack to the WHILEM, then we
+             * make a note that this particular WHILEM op was at string
+             * position 47 (say) when the rest of pattern failed. Then, if
+             * we ever find ourselves back at that WHILEM, and at string
+             * position 47 again, we can just fail immediately rather than
+             * running the rest of the pattern again.
+             *
+             * This is very handy when patterns start to go
+             * 'super-linear', like in (a+)*(a+)*(a+)*, where you end up
+             * with a combinatorial explosion of backtracking.
+             *
+             * The cache is implemented as a bit array, with one bit per
+             * string byte position per WHILEM op (up to 16) - so its
+             * between 0.25 and 2x the string size.
+             *
+             * To avoid allocating a poscache buffer every time, we do an
+             * initially countdown; only after we have  executed a WHILEM
+             * op (string-length x #WHILEMs) times do we allocate the
+             * cache.
+             *
+             * The top 4 bits of scan->flags byte say how many different
+             * relevant CURLLYX/WHILEM op pairs there are, while the
+             * bottom 4-bits is the identifying index number of this
+             * WHILEM.
+             */
 
            if (scan->flags) {
 
-               if (!PL_reg_maxiter) {
+               if (!reginfo->poscache_maxiter) {
                    /* start the countdown: Postpone detection until we
                     * know the match is not *that* much linear. */
-                   PL_reg_maxiter = (PL_regeol - PL_bostr + 1) * (scan->flags>>4);
+                   reginfo->poscache_maxiter
+                        =    (reginfo->strend - reginfo->strbeg + 1)
+                           * (scan->flags>>4);
                    /* possible overflow for long strings and many CURLYX's */
-                   if (PL_reg_maxiter < 0)
-                       PL_reg_maxiter = I32_MAX;
-                   PL_reg_leftiter = PL_reg_maxiter;
+                   if (reginfo->poscache_maxiter < 0)
+                       reginfo->poscache_maxiter = I32_MAX;
+                   reginfo->poscache_iter = reginfo->poscache_maxiter;
                }
 
-               if (PL_reg_leftiter-- == 0) {
+               if (reginfo->poscache_iter-- == 0) {
                    /* initialise cache */
-                   const I32 size = (PL_reg_maxiter + 7)/8;
-                   if (PL_reg_poscache) {
-                       if ((I32)PL_reg_poscache_size < size) {
-                           Renew(PL_reg_poscache, size, char);
-                           PL_reg_poscache_size = size;
+                   const I32 size = (reginfo->poscache_maxiter + 7)/8;
+                    regmatch_info_aux *const aux = reginfo->info_aux;
+                   if (aux->poscache) {
+                       if ((I32)reginfo->poscache_size < size) {
+                           Renew(aux->poscache, size, char);
+                           reginfo->poscache_size = size;
                        }
-                       Zero(PL_reg_poscache, size, char);
+                       Zero(aux->poscache, size, char);
                    }
                    else {
-                       PL_reg_poscache_size = size;
-                       Newxz(PL_reg_poscache, size, char);
+                       reginfo->poscache_size = size;
+                       Newxz(aux->poscache, size, char);
                    }
                    DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
       "%swhilem: Detected a super-linear match, switching on caching%s...\n",
@@ -5473,14 +5576,17 @@ NULL
                    );
                }
 
-               if (PL_reg_leftiter < 0) {
+               if (reginfo->poscache_iter < 0) {
                    /* have we already failed at this position? */
                    I32 offset, mask;
+
+                    reginfo->poscache_iter = -1; /* stop eventual underflow */
                    offset  = (scan->flags & 0xf) - 1
-                               + (locinput - PL_bostr)  * (scan->flags>>4);
+                                +   (locinput - reginfo->strbeg)
+                                  * (scan->flags>>4);
                    mask    = 1 << (offset % 8);
                    offset /= 8;
-                   if (PL_reg_poscache[offset] & mask) {
+                   if (reginfo->info_aux->poscache[offset] & mask) {
                        DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
                            "%*s  whilem: (cache) already tried at this position...\n",
                            REPORT_CODE_OFF+depth*2, "")
@@ -5552,9 +5658,9 @@ NULL
          do_whilem_B_max:
            if (cur_curlyx->u.curlyx.count >= REG_INFTY
                && ckWARN(WARN_REGEXP)
-               && !(PL_reg_flags & RF_warned))
+               && !reginfo->warned)
            {
-               PL_reg_flags |= RF_warned;
+                reginfo->warned        = TRUE;
                Perl_warner(aTHX_ packWARN(WARN_REGEXP),
                     "Complex regular subexpression recursion limit (%d) "
                     "exceeded",
@@ -5577,9 +5683,9 @@ NULL
                /* Maximum greed exceeded */
                if (cur_curlyx->u.curlyx.count >= REG_INFTY
                    && ckWARN(WARN_REGEXP)
-                   && !(PL_reg_flags & RF_warned))
+                    && !reginfo->warned)
                {
-                   PL_reg_flags |= RF_warned;
+                    reginfo->warned    = TRUE;
                    Perl_warner(aTHX_ packWARN(WARN_REGEXP),
                        "Complex regular subexpression recursion "
                        "limit (%d) exceeded",
@@ -5715,7 +5821,7 @@ NULL
            ST.count++;
            /* after first match, determine A's length: u.curlym.alen */
            if (ST.count == 1) {
-               if (PL_reg_match_utf8) {
+               if (reginfo->is_utf8_target) {
                    char *s = st->locinput;
                    while (s < locinput) {
                        ST.alen++;
@@ -5774,7 +5880,8 @@ NULL
                     */
                    if (PL_regkind[OP(text_node)] == EXACT) {
                         if (! S_setup_EXACTISH_ST_c1_c2(aTHX_
-                           text_node, &ST.c1, ST.c1_utf8, &ST.c2, ST.c2_utf8))
+                           text_node, &ST.c1, ST.c1_utf8, &ST.c2, ST.c2_utf8,
+                           reginfo))
                         {
                             sayNO;
                         }
@@ -5824,8 +5931,8 @@ NULL
                I32 paren = ST.me->flags;
                if (ST.count) {
                    rex->offs[paren].start
-                       = HOPc(locinput, -ST.alen) - PL_bostr;
-                   rex->offs[paren].end = locinput - PL_bostr;
+                       = HOPc(locinput, -ST.alen) - reginfo->strbeg;
+                   rex->offs[paren].end = locinput - reginfo->strbeg;
                    if ((U32)paren > rex->lastparen)
                        rex->lastparen = paren;
                    rex->lastcloseparen = paren;
@@ -5867,8 +5974,8 @@ NULL
 #define CURLY_SETPAREN(paren, success) \
     if (paren) { \
        if (success) { \
-           rex->offs[paren].start = HOPc(locinput, -1) - PL_bostr; \
-           rex->offs[paren].end = locinput - PL_bostr; \
+           rex->offs[paren].start = HOPc(locinput, -1) - reginfo->strbeg; \
+           rex->offs[paren].end = locinput - reginfo->strbeg; \
            if (paren > rex->lastparen) \
                rex->lastparen = paren; \
            rex->lastcloseparen = paren; \
@@ -5950,7 +6057,8 @@ NULL
                         if this changes back then the macro for IS_TEXT and 
                         friends need to change. */
                         if (! S_setup_EXACTISH_ST_c1_c2(aTHX_
-                           text_node, &ST.c1, ST.c1_utf8, &ST.c2, ST.c2_utf8))
+                           text_node, &ST.c1, ST.c1_utf8, &ST.c2, ST.c2_utf8,
+                           reginfo))
                         {
                             sayNO;
                         }
@@ -5963,7 +6071,9 @@ NULL
            if (minmod) {
                 char *li = locinput;
                minmod = 0;
-               if (ST.min && regrepeat(rex, &li, ST.A, ST.min, depth) < ST.min)
+               if (ST.min &&
+                        regrepeat(rex, &li, ST.A, reginfo, ST.min, depth)
+                            < ST.min)
                    sayNO;
                 SET_locinput(li);
                ST.count = ST.min;
@@ -5976,7 +6086,7 @@ NULL
                /* set ST.maxpos to the furthest point along the
                 * string that could possibly match */
                if  (ST.max == REG_INFTY) {
-                   ST.maxpos = PL_regeol - 1;
+                   ST.maxpos = reginfo->strend - 1;
                    if (utf8_target)
                        while (UTF8_IS_CONTINUATION(*(U8*)ST.maxpos))
                            ST.maxpos--;
@@ -5984,13 +6094,13 @@ NULL
                else if (utf8_target) {
                    int m = ST.max - ST.min;
                    for (ST.maxpos = locinput;
-                        m >0 && ST.maxpos < PL_regeol; m--)
+                        m >0 && ST.maxpos < reginfo->strend; m--)
                        ST.maxpos += UTF8SKIP(ST.maxpos);
                }
                else {
                    ST.maxpos = locinput + ST.max - ST.min;
-                   if (ST.maxpos >= PL_regeol)
-                       ST.maxpos = PL_regeol - 1;
+                   if (ST.maxpos >= reginfo->strend)
+                       ST.maxpos = reginfo->strend - 1;
                }
                goto curly_try_B_min_known;
 
@@ -5999,7 +6109,7 @@ NULL
                 /* avoid taking address of locinput, so it can remain
                  * a register var */
                 char *li = locinput;
-               ST.count = regrepeat(rex, &li, ST.A, ST.max, depth);
+               ST.count = regrepeat(rex, &li, ST.A, reginfo, ST.max, depth);
                if (ST.count < ST.min)
                    sayNO;
                 SET_locinput(li);
@@ -6083,7 +6193,7 @@ NULL
                      * locinput matches */
                     char *li = ST.oldloc;
                    ST.count += n;
-                   if (regrepeat(rex, &li, ST.A, n, depth) < n)
+                   if (regrepeat(rex, &li, ST.A, reginfo, n, depth) < n)
                        sayNO;
                     assert(n == REG_INFTY || locinput == li);
                }
@@ -6107,7 +6217,7 @@ NULL
            /* failed -- move forward one */
             {
                 char *li = locinput;
-                if (!regrepeat(rex, &li, ST.A, 1, depth)) {
+                if (!regrepeat(rex, &li, ST.A, reginfo, 1, depth)) {
                     sayNO;
                 }
                 locinput = li;
@@ -6137,7 +6247,7 @@ NULL
                 goto fake_end;
             }
            {
-               bool could_match = locinput < PL_regeol;
+               bool could_match = locinput < reginfo->strend;
 
                /* If it could work, try it. */
                 if (ST.c1 != CHRTEST_VOID && could_match) {
@@ -6182,15 +6292,13 @@ NULL
            fake_end:
            if (cur_eval) {
                /* we've just finished A in /(??{A})B/; now continue with B */
-               st->u.eval.toggle_reg_flags
-                           = cur_eval->u.eval.toggle_reg_flags;
-               PL_reg_flags ^= st->u.eval.toggle_reg_flags; 
 
                st->u.eval.prev_rex = rex_sv;           /* inner */
 
                 /* Save *all* the positions. */
                st->u.eval.cp = regcppush(rex, 0, maxopenparen);
                rex_sv = cur_eval->u.eval.prev_rex;
+               is_utf8_pat = reginfo->is_utf8_pat = cBOOL(RX_UTF8(rex_sv));
                SET_reg_curpm(rex_sv);
                rex = ReANY(rex_sv);
                rexi = RXi_GET(rex);
@@ -6219,8 +6327,8 @@ NULL
                DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                                      "%sMatch possible, but length=%ld is smaller than requested=%ld, failing!%s\n",
                                      PL_colors[4],
-                                     (long)(locinput - PL_reg_starttry),
-                                     (long)(reginfo->till - PL_reg_starttry),
+                                     (long)(locinput - startpos),
+                                     (long)(reginfo->till - startpos),
                                      PL_colors[5]));
                                                      
                sayNO_SILENT;           /* Cannot match: too short. */
@@ -6312,7 +6420,7 @@ NULL
            break;
 
        case COMMIT:  /*  (*COMMIT)  */
-           reginfo->cutpoint = PL_regeol;
+           reginfo->cutpoint = reginfo->strend;
            /* FALLTHROUGH */
 
        case PRUNE:   /*  (*PRUNE)   */
@@ -6412,7 +6520,7 @@ NULL
 #undef ST
 
         case LNBREAK: /* \R */
-            if ((n=is_LNBREAK_safe(locinput, PL_regeol, utf8_target))) {
+            if ((n=is_LNBREAK_safe(locinput, reginfo->strend, utf8_target))) {
                 locinput += n;
             } else
                 sayNO;
@@ -6430,7 +6538,7 @@ NULL
             if (utf8_target) {
                 locinput += PL_utf8skip[nextchr];
                 /* locinput is allowed to go 1 char off the end, but not 2+ */
-                if (locinput > PL_regeol)
+                if (locinput > reginfo->strend)
                     sayNO;
             }
             else
@@ -6542,7 +6650,7 @@ yes:
     DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%sMatch successful!%s\n",
                          PL_colors[4], PL_colors[5]));
 
-    if (PL_reg_state.re_state_eval_setup_done) {
+    if (reginfo->info_aux_eval) {
        /* each successfully executed (?{...}) block does the equivalent of
         *   local $^R = do {...}
         * When popping the save stack, all these locals would be undone;
@@ -6614,11 +6722,8 @@ no_silent:
         PERL_UNUSED_VAR(SP);
     }
 
-    /* clean up; in particular, free all slabs above current one */
-    LEAVE_SCOPE(oldsave);
-
-    assert(!result ||  locinput - PL_bostr >= 0);
-    return result ?  locinput - PL_bostr : -1;
+    assert(!result ||  locinput - reginfo->strbeg >= 0);
+    return result ?  locinput - reginfo->strbeg : -1;
 }
 
 /*
@@ -6631,18 +6736,20 @@ no_silent:
  *             to point to the byte following the highest successful
  *             match.
  * p         - the regnode to be repeatedly matched against.
+ * reginfo   - struct holding match state, such as strend
  * max       - maximum number of things to match.
  * depth     - (for debugging) backtracking depth.
  */
 STATIC I32
-S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 max, int depth)
+S_regrepeat(pTHX_ regexp *prog, char **startposp, const regnode *p,
+            regmatch_info *const reginfo, I32 max, int depth)
 {
     dVAR;
     char *scan;     /* Pointer to current position in target string */
     I32 c;
-    char *loceol = PL_regeol;   /* local version */
+    char *loceol = reginfo->strend;   /* local version */
     I32 hardcount = 0;  /* How many matches so far */
-    bool utf8_target = PL_reg_match_utf8;
+    bool utf8_target = reginfo->is_utf8_target;
     int to_complement = 0;  /* Invert the result? */
     UV utf8_flags;
     _char_class_number classnum;
@@ -6655,7 +6762,7 @@ S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 ma
     scan = *startposp;
     if (max == REG_INFTY)
        max = I32_MAX;
-    else if (! utf8_target && scan + max < loceol)
+    else if (! utf8_target && loceol - scan > max)
        loceol = scan + max;
 
     /* Here, for the case of a non-UTF-8 target we have adjusted <loceol> down
@@ -6704,7 +6811,7 @@ S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 ma
            scan = loceol;
        break;
     case CANY:  /* Move <scan> forward <max> bytes, unless goes off end */
-        if (utf8_target && scan + max < loceol) {
+        if (utf8_target && loceol - scan > max) {
 
             /* <loceol> hadn't been adjusted in the UTF-8 case */
             scan +=  max;
@@ -6714,7 +6821,7 @@ S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 ma
         }
        break;
     case EXACT:
-        assert(STR_LEN(p) == (UTF_PATTERN) ? UTF8SKIP(STRING(p)) : 1);
+        assert(STR_LEN(p) == reginfo->is_utf8_pat ? UTF8SKIP(STRING(p)) : 1);
 
        c = (U8)*STRING(p);
 
@@ -6722,8 +6829,8 @@ S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 ma
          * under UTF-8, or both target and pattern aren't UTF-8.  Note that we
          * can use UTF8_IS_INVARIANT() even if the pattern isn't UTF-8, as it's
          * true iff it doesn't matter if the argument is in UTF-8 or not */
-        if (UTF8_IS_INVARIANT(c) || (! utf8_target && ! UTF_PATTERN)) {
-            if (utf8_target && scan + max < loceol) {
+        if (UTF8_IS_INVARIANT(c) || (! utf8_target && ! reginfo->is_utf8_pat)) {
+            if (utf8_target && loceol - scan > max) {
                 /* We didn't adjust <loceol> because is UTF-8, but ok to do so,
                  * since here, to match at all, 1 char == 1 byte */
                 loceol = scan + max;
@@ -6732,7 +6839,7 @@ S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 ma
                scan++;
            }
        }
-       else if (UTF_PATTERN) {
+       else if (reginfo->is_utf8_pat) {
             if (utf8_target) {
                 STRLEN scan_char_len;
 
@@ -6783,7 +6890,7 @@ S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 ma
        goto do_exactf;
 
     case EXACTFL:
-       PL_reg_flags |= RF_tainted;
+        RXp_MATCH_TAINTED_on(prog);
        utf8_flags = FOLDEQ_UTF8_LOCALE;
        goto do_exactf;
 
@@ -6794,26 +6901,28 @@ S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 ma
     case EXACTFU_SS:
     case EXACTFU_TRICKYFOLD:
     case EXACTFU:
-       utf8_flags = (UTF_PATTERN) ? FOLDEQ_S2_ALREADY_FOLDED : 0;
+       utf8_flags = reginfo->is_utf8_pat ? FOLDEQ_S2_ALREADY_FOLDED : 0;
 
     do_exactf: {
         int c1, c2;
         U8 c1_utf8[UTF8_MAXBYTES+1], c2_utf8[UTF8_MAXBYTES+1];
 
-        assert(STR_LEN(p) == (UTF_PATTERN) ? UTF8SKIP(STRING(p)) : 1);
+        assert(STR_LEN(p) == reginfo->is_utf8_pat ? UTF8SKIP(STRING(p)) : 1);
 
-        if (S_setup_EXACTISH_ST_c1_c2(aTHX_ p, &c1, c1_utf8, &c2, c2_utf8)) {
+        if (S_setup_EXACTISH_ST_c1_c2(aTHX_ p, &c1, c1_utf8, &c2, c2_utf8,
+                                        reginfo))
+        {
             if (c1 == CHRTEST_VOID) {
                 /* Use full Unicode fold matching */
-                char *tmpeol = PL_regeol;
-                STRLEN pat_len = (UTF_PATTERN) ? UTF8SKIP(STRING(p)) : 1;
+                char *tmpeol = reginfo->strend;
+                STRLEN pat_len = reginfo->is_utf8_pat ? UTF8SKIP(STRING(p)) : 1;
                 while (hardcount < max
                         && foldEQ_utf8_flags(scan, &tmpeol, 0, utf8_target,
                                              STRING(p), NULL, pat_len,
-                                             cBOOL(UTF_PATTERN), utf8_flags))
+                                             reginfo->is_utf8_pat, utf8_flags))
                 {
                     scan = tmpeol;
-                    tmpeol = PL_regeol;
+                    tmpeol = reginfo->strend;
                     hardcount++;
                 }
             }
@@ -6854,6 +6963,7 @@ S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 ma
        break;
     }
     case ANYOF:
+    case ANYOF_WARN_SUPER:
        if (utf8_target) {
            while (hardcount < max
                    && scan < loceol
@@ -6875,7 +6985,7 @@ S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 ma
         /* FALLTHROUGH */
 
     case POSIXL:
-       PL_reg_flags |= RF_tainted;
+        RXp_MATCH_TAINTED_on(prog);
        if (! utf8_target) {
            while (scan < loceol && to_complement ^ cBOOL(isFOO_lc(FLAGS(p),
                                                                    *scan)))
@@ -6900,7 +7010,7 @@ S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 ma
         /* FALLTHROUGH */
 
     case POSIXA:
-        if (utf8_target && scan + max < loceol) {
+        if (utf8_target && loceol - scan > max) {
 
             /* We didn't adjust <loceol> at the beginning of this routine
              * because is UTF-8, but it is actually ok to do so, since here, to
@@ -7086,7 +7196,7 @@ S_regrepeat(pTHX_ const regexp *prog, char **startposp, const regnode *p, I32 ma
             /* LNBREAK can match one or two latin chars, which is ok, but we
              * have to use hardcount in this situation, and throw away the
              * adjustment to <loceol> done before the switch statement */
-            loceol = PL_regeol;
+            loceol = reginfo->strend;
            while (scan < loceol && (c=is_LNBREAK_latin1_safe(scan, loceol))) {
                scan+=c;
                hardcount++;
@@ -7161,15 +7271,18 @@ STATIC SV *
 S_core_regclass_swash(pTHX_ const regexp *prog, const regnode* node, bool doinit, SV** listsvp)
 {
     /* Returns the swash for the input 'node' in the regex 'prog'.
-     * If <doinit> is true, will attempt to create the swash if not already
+     * If <doinit> is 'true', will attempt to create the swash if not already
      *   done.
-     * If <listsvp> is non-null, will return the swash initialization string in
-     *   it.
+     * 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).
      * Tied intimately to how regcomp.c sets up the data structure */
 
     dVAR;
     SV *sw  = NULL;
-    SV *si  = NULL;
+    SV *si  = NULL;         /* Input swash initialization string */
     SV*  invlist = NULL;
 
     RXi_GET_DECL(prog,progi);
@@ -7222,16 +7335,18 @@ S_core_regclass_swash(pTHX_ const regexp *prog, const regnode* node, bool doinit
        }
     }
        
+    /* If requested, return a printable version of what this swash matches */
     if (listsvp) {
        SV* matches_string = newSVpvn("", 0);
 
-       /* Use the swash, if any, which has to have incorporated into it all
-        * possibilities */
+        /* 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))
         {
-
-           /* If no swash, use the input initialization string, if available */
            sv_catsv(matches_string, si);
        }
 
@@ -7262,7 +7377,7 @@ S_core_regclass_swash(pTHX_ const regexp *prog, const regnode* node, bool doinit
  */
 
 STATIC bool
-S_reginclass(pTHX_ const regexp * const prog, const regnode * const n, const U8* const p, const bool utf8_target)
+S_reginclass(pTHX_ regexp * const prog, const regnode * const n, const U8* const p, const bool utf8_target)
 {
     dVAR;
     const char flags = ANYOF_FLAGS(n);
@@ -7295,7 +7410,7 @@ S_reginclass(pTHX_ const regexp * const prog, const regnode * const n, const U8*
            match = TRUE;
        }
        else if (flags & ANYOF_LOCALE) {
-           PL_reg_flags |= RF_tainted;
+           RXp_MATCH_TAINTED_on(prog);
 
            if ((flags & ANYOF_LOC_FOLD)
                 && ANYOF_BITMAP_TEST(n, PL_fold_locale[c]))
@@ -7322,7 +7437,17 @@ S_reginclass(pTHX_ const regexp * const prog, const regnode * const n, const U8*
                  * will be 1, so the exclusive or will reverse things, so we
                  * are testing for \W.  On the third iteration, 'to_complement'
                  * will be 0, and we would be testing for \s; the fourth
-                 * iteration would test for \S, etc. */
+                 * iteration would test for \S, etc.
+                 *
+                 * Note that this code assumes that all the classes are closed
+                 * under folding.  For example, if a character matches \w, then
+                 * its fold does too; and vice versa.  This should be true for
+                 * any well-behaved locale for all the currently defined Posix
+                 * classes, except for :lower: and :upper:, which are handled
+                 * by the pseudo-class :cased: which matches if either of the
+                 * other two does.  To get rid of this assumption, an outer
+                 * loop could be used below to iterate over both the source
+                 * character, and its fold (if different) */
 
                 int count = 0;
                 int to_complement = 0;
@@ -7358,7 +7483,7 @@ S_reginclass(pTHX_ const regexp * const prog, const regnode * const n, const U8*
                     || (utf8_target
                         && (c >=256
                             || (! (flags & ANYOF_LOCALE))
-                            || (flags & ANYOF_IS_SYNTHETIC)))))
+                            || OP(n) == ANYOF_SYNTHETIC))))
        {
            SV * const sw = core_regclass_swash(prog, n, TRUE, 0);
            if (sw) {
@@ -7380,7 +7505,7 @@ S_reginclass(pTHX_ const regexp * const prog, const regnode * const n, const U8*
        }
 
         if (UNICODE_IS_SUPER(c)
-            && (flags & ANYOF_WARN_SUPER)
+            && OP(n) == ANYOF_WARN_SUPER
             && ckWARN_d(WARN_NON_UNICODE))
         {
             Perl_warner(aTHX_ packWARN(WARN_NON_UNICODE),
@@ -7484,28 +7609,143 @@ S_reghopmaybe3(U8* s, I32 off, const U8* lim)
     return s;
 }
 
+
+/* when executing a regex that may have (?{}), extra stuff needs setting
+   up that will be visible to the called code, even before the current
+   match has finished. In particular:
+
+   * $_ is localised to the SV currently being matched;
+   * pos($_) is created if necessary, ready to be updated on each call-out
+     to code;
+   * a fake PMOP is created that can be set to PL_curpm (normally PL_curpm
+     isn't set until the current pattern is successfully finished), so that
+     $1 etc of the match-so-far can be seen;
+   * save the old values of subbeg etc of the current regex, and  set then
+     to the current string (again, this is normally only done at the end
+     of execution)
+*/
+
+static void
+S_setup_eval_state(pTHX_ regmatch_info *const reginfo)
+{
+    MAGIC *mg;
+    regexp *const rex = ReANY(reginfo->prog);
+    regmatch_info_aux_eval *eval_state = reginfo->info_aux_eval;
+
+    eval_state->rex = rex;
+
+    if (reginfo->sv) {
+        /* Make $_ available to executed code. */
+        if (reginfo->sv != DEFSV) {
+            SAVE_DEFSV;
+            DEFSV_set(reginfo->sv);
+        }
+
+        if (!(mg = mg_find_mglob(reginfo->sv))) {
+            /* prepare for quick setting of pos */
+            mg = sv_magicext_mglob(reginfo->sv);
+            mg->mg_len = -1;
+        }
+        eval_state->pos_magic = mg;
+        eval_state->pos       = mg->mg_len;
+    }
+    else
+        eval_state->pos_magic = NULL;
+
+    if (!PL_reg_curpm) {
+        /* PL_reg_curpm is a fake PMOP that we can attach the current
+         * regex to and point PL_curpm at, so that $1 et al are visible
+         * within a /(?{})/. It's just allocated once per interpreter the
+         * first time its needed */
+        Newxz(PL_reg_curpm, 1, PMOP);
+#ifdef USE_ITHREADS
+        {
+            SV* const repointer = &PL_sv_undef;
+            /* this regexp is also owned by the new PL_reg_curpm, which
+               will try to free it.  */
+            av_push(PL_regex_padav, repointer);
+            PL_reg_curpm->op_pmoffset = av_len(PL_regex_padav);
+            PL_regex_pad = AvARRAY(PL_regex_padav);
+        }
+#endif
+    }
+    SET_reg_curpm(reginfo->prog);
+    eval_state->curpm = PL_curpm;
+    PL_curpm = PL_reg_curpm;
+    if (RXp_MATCH_COPIED(rex)) {
+        /*  Here is a serious problem: we cannot rewrite subbeg,
+            since it may be needed if this match fails.  Thus
+            $` inside (?{}) could fail... */
+        eval_state->subbeg     = rex->subbeg;
+        eval_state->sublen     = rex->sublen;
+        eval_state->suboffset  = rex->suboffset;
+        eval_state->subcoffset = rex->subcoffset;
+#ifdef PERL_ANY_COW
+        eval_state->saved_copy = rex->saved_copy;
+#endif
+        RXp_MATCH_COPIED_off(rex);
+    }
+    else
+        eval_state->subbeg = NULL;
+    rex->subbeg = (char *)reginfo->strbeg;
+    rex->suboffset = 0;
+    rex->subcoffset = 0;
+    rex->sublen = reginfo->strend - reginfo->strbeg;
+}
+
+
+/* destructor to clear up regmatch_info_aux and regmatch_info_aux_eval */
+
 static void
-restore_pos(pTHX_ void *arg)
+S_cleanup_regmatch_info_aux(pTHX_ void *arg)
 {
     dVAR;
-    regexp * const rex = (regexp *)arg;
-    if (PL_reg_state.re_state_eval_setup_done) {
-       if (PL_reg_oldsaved) {
-           rex->subbeg = PL_reg_oldsaved;
-           rex->sublen = PL_reg_oldsavedlen;
-           rex->suboffset = PL_reg_oldsavedoffset;
-           rex->subcoffset = PL_reg_oldsavedcoffset;
+    regmatch_info_aux *aux = (regmatch_info_aux *) arg;
+    regmatch_info_aux_eval *eval_state =  aux->info_aux_eval;
+    regmatch_slab *s;
+
+    Safefree(aux->poscache);
+
+    if (eval_state) {
+
+        /* undo the effects of S_setup_eval_state() */
+
+        if (eval_state->subbeg) {
+            regexp * const rex = eval_state->rex;
+            rex->subbeg     = eval_state->subbeg;
+            rex->sublen     = eval_state->sublen;
+            rex->suboffset  = eval_state->suboffset;
+            rex->subcoffset = eval_state->subcoffset;
 #ifdef PERL_ANY_COW
-           rex->saved_copy = PL_nrs;
+            rex->saved_copy = eval_state->saved_copy;
 #endif
-           RXp_MATCH_COPIED_on(rex);
-       }
-       PL_reg_magic->mg_len = PL_reg_oldpos;
-       PL_reg_state.re_state_eval_setup_done = FALSE;
-       PL_curpm = PL_reg_oldcurpm;
-    }  
+            RXp_MATCH_COPIED_on(rex);
+        }
+        if (eval_state->pos_magic)
+            eval_state->pos_magic->mg_len = eval_state->pos;
+
+        PL_curpm = eval_state->curpm;
+    }
+
+    PL_regmatch_state = aux->old_regmatch_state;
+    PL_regmatch_slab  = aux->old_regmatch_slab;
+
+    /* free all slabs above current one - this must be the last action
+     * of this function, as aux and eval_state are allocated within
+     * slabs and may be freed here */
+
+    s = PL_regmatch_slab->next;
+    if (s) {
+        PL_regmatch_slab->next = NULL;
+        while (s) {
+            regmatch_slab * const osl = s;
+            s = s->next;
+            Safefree(osl);
+        }
+    }
 }
 
+
 STATIC void
 S_to_utf8_substr(pTHX_ regexp *prog)
 {