This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
Add perlintern.pod documentation docatch + prescan_version
[perl5.git] / regexec.c
index b05a177..17a0dc6 100644 (file)
--- a/regexec.c
+++ b/regexec.c
@@ -2,7 +2,11 @@
  */
 
 /*
- * "One Ring to rule them all, One Ring to find them..."
+ *     One Ring to rule them all, One Ring to find them
+ &
+ *     [p.v of _The Lord of the Rings_, opening poem]
+ *     [p.50 of _The Lord of the Rings_, I/iii: "The Shadow of the Past"]
+ *     [p.254 of _The Lord of the Rings_, II/ii: "The Council of Elrond"]
  */
 
 /* This file contains functions for executing a regular expression.  See
@@ -56,7 +60,8 @@
  ****    Alterations to Henry's code are...
  ****
  ****    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
- ****    2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 by Larry Wall and others
+ ****    2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ ****    by Larry Wall and others
  ****
  ****    You may distribute under the terms of either the GNU General Public
  ****    License or the Artistic License, as specified in the README file.
 #define HOP3(pos,off,lim) (PL_reg_match_utf8 ? reghop3((U8*)(pos), off, (U8*)(lim)) : (U8*)(pos + off))
 #define HOP3c(pos,off,lim) ((char*)HOP3(pos,off,lim))
 
+/* 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); assert(ok); 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 ok; ENTER; save_re_context(); ok=CAT2(is_utf8_,class)((const U8*)" "); 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_SPACE() LOAD_UTF8_CHARCLASS(space," ")
-#define LOAD_UTF8_CHARCLASS_MARK()  LOAD_UTF8_CHARCLASS(mark, "\xcd\x86")
+
+#define LOAD_UTF8_CHARCLASS_GCB()  /* Grapheme cluster boundaries */        \
+       LOAD_UTF8_CHARCLASS(X_begin, " ");                                  \
+       LOAD_UTF8_CHARCLASS(X_non_hangul, "A");                             \
+       /* These are utf8 constants, and not utf-ebcdic constants, so the   \
+           * assert should likely and hopefully fail on an EBCDIC machine */ \
+       LOAD_UTF8_CHARCLASS(X_extend, "\xcc\x80"); /* U+0300 */             \
+                                                                           \
+       /* No asserts are done for these, in case called on an early        \
+           * Unicode version in which they map to nothing */               \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_prepend);/* U+0E40 "\xe0\xb9\x80" */ \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_L);          /* U+1100 "\xe1\x84\x80" */ \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_LV);     /* U+AC00 "\xea\xb0\x80" */ \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_LVT);    /* U+AC01 "\xea\xb0\x81" */ \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_LV_LVT_V);/* U+AC01 "\xea\xb0\x81" */\
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_T);      /* U+11A8 "\xe1\x86\xa8" */ \
+       LOAD_UTF8_CHARCLASS_NO_CHECK(X_V)       /* U+1160 "\xe1\x85\xa0" */  
+
+/* 
+   We dont use PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS as the direct test
+   so that it is possible to override the option here without having to 
+   rebuild the entire core. as we are required to do if we change regcomp.h
+   which is where PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS is defined.
+*/
+#if PERL_LEGACY_UNICODE_CHARCLASS_MAPPINGS
+#define BROKEN_UNICODE_CHARCLASS_MAPPINGS
+#endif
+
+#ifdef BROKEN_UNICODE_CHARCLASS_MAPPINGS
+#define LOAD_UTF8_CHARCLASS_PERL_WORD()   LOAD_UTF8_CHARCLASS_ALNUM()
+#define LOAD_UTF8_CHARCLASS_PERL_SPACE()  LOAD_UTF8_CHARCLASS_SPACE()
+#define LOAD_UTF8_CHARCLASS_POSIX_DIGIT() LOAD_UTF8_CHARCLASS_DIGIT()
+#define RE_utf8_perl_word   PL_utf8_alnum
+#define RE_utf8_perl_space  PL_utf8_space
+#define RE_utf8_posix_digit PL_utf8_digit
+#define perl_word  alnum
+#define perl_space space
+#define posix_digit digit
+#else
+#define LOAD_UTF8_CHARCLASS_PERL_WORD()   LOAD_UTF8_CHARCLASS(perl_word,"a")
+#define LOAD_UTF8_CHARCLASS_PERL_SPACE()  LOAD_UTF8_CHARCLASS(perl_space," ")
+#define LOAD_UTF8_CHARCLASS_POSIX_DIGIT() LOAD_UTF8_CHARCLASS(posix_digit,"0")
+#define RE_utf8_perl_word   PL_utf8_perl_word
+#define RE_utf8_perl_space  PL_utf8_perl_space
+#define RE_utf8_posix_digit PL_utf8_posix_digit
+#endif
+
+
+#define CCC_TRY_AFF(NAME,NAMEL,CLASS,STR,LCFUNC_utf8,FUNC,LCFUNC)                          \
+        case NAMEL:                                                              \
+            PL_reg_flags |= RF_tainted;                                                 \
+            /* FALL THROUGH */                                                          \
+        case NAME:                                                                     \
+            if (!nextchr)                                                               \
+                sayNO;                                                                  \
+            if (do_utf8 && UTF8_IS_CONTINUED(nextchr)) {                                \
+                if (!CAT2(PL_utf8_,CLASS)) {                                            \
+                    bool ok;                                                            \
+                    ENTER;                                                              \
+                    save_re_context();                                                  \
+                    ok=CAT2(is_utf8_,CLASS)((const U8*)STR);                            \
+                    assert(ok);                                                         \
+                    LEAVE;                                                              \
+                }                                                                       \
+                if (!(OP(scan) == NAME                                                  \
+                    ? (bool)swash_fetch(CAT2(PL_utf8_,CLASS), (U8*)locinput, do_utf8)   \
+                    : LCFUNC_utf8((U8*)locinput)))                                      \
+                {                                                                       \
+                    sayNO;                                                              \
+                }                                                                       \
+                locinput += PL_utf8skip[nextchr];                                       \
+                nextchr = UCHARAT(locinput);                                            \
+                break;                                                                  \
+            }                                                                           \
+            if (!(OP(scan) == NAME ? FUNC(nextchr) : LCFUNC(nextchr)))                  \
+                sayNO;                                                                  \
+            nextchr = UCHARAT(++locinput);                                              \
+            break
+
+#define CCC_TRY_NEG(NAME,NAMEL,CLASS,STR,LCFUNC_utf8,FUNC,LCFUNC)                        \
+        case NAMEL:                                                              \
+            PL_reg_flags |= RF_tainted;                                                 \
+            /* FALL THROUGH */                                                          \
+        case NAME :                                                                     \
+            if (!nextchr && locinput >= PL_regeol)                                      \
+                sayNO;                                                                  \
+            if (do_utf8 && UTF8_IS_CONTINUED(nextchr)) {                                \
+                if (!CAT2(PL_utf8_,CLASS)) {                                            \
+                    bool ok;                                                            \
+                    ENTER;                                                              \
+                    save_re_context();                                                  \
+                    ok=CAT2(is_utf8_,CLASS)((const U8*)STR);                            \
+                    assert(ok);                                                         \
+                    LEAVE;                                                              \
+                }                                                                       \
+                if ((OP(scan) == NAME                                                  \
+                    ? (bool)swash_fetch(CAT2(PL_utf8_,CLASS), (U8*)locinput, do_utf8)    \
+                    : LCFUNC_utf8((U8*)locinput)))                                      \
+                {                                                                       \
+                    sayNO;                                                              \
+                }                                                                       \
+                locinput += PL_utf8skip[nextchr];                                       \
+                nextchr = UCHARAT(locinput);                                            \
+                break;                                                                  \
+            }                                                                           \
+            if ((OP(scan) == NAME ? FUNC(nextchr) : LCFUNC(nextchr)))                   \
+                sayNO;                                                                  \
+            nextchr = UCHARAT(++locinput);                                              \
+            break
+
+
+
+
 
 /* TODO: Combine JUMPABLE and HAS_TEXT to cache OP(rn) */
 
@@ -237,9 +360,10 @@ S_regcppop(pTHX_ const regexp *rex)
     dVAR;
     U32 i;
     char *input;
-
     GET_RE_DEBUG_FLAGS_DECL;
 
+    PERL_ARGS_ASSERT_REGCPPOP;
+
     /* Pop REGCP_OTHER_ELEMS before the parentheses loop starts. */
     i = SSPOPINT;
     assert(i == SAVEt_REGCONTEXT); /* Check that the magic cookie is there. */
@@ -314,6 +438,8 @@ Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, register char *strend,
 /* minend: end of match must be >=minend after stringarg. */
 /* nosave: For optimizations. */
 {
+    PERL_ARGS_ASSERT_PREGEXEC;
+
     return
        regexec_flags(prog, stringarg, strend, strbeg, minend, screamer, NULL,
                      nosave ? 0 : REXEC_COPY_STR);
@@ -371,10 +497,11 @@ Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, register char *strend,
    deleted from the finite automaton. */
 
 char *
-Perl_re_intuit_start(pTHX_ REGEXP * const prog, SV *sv, char *strpos,
+Perl_re_intuit_start(pTHX_ REGEXP * const rx, SV *sv, char *strpos,
                     char *strend, const U32 flags, re_scream_pos_data *data)
 {
     dVAR;
+    struct regexp *const prog = (struct regexp *)SvANY(rx);
     register I32 start_shift = 0;
     /* Should be nonnegative! */
     register I32 end_shift   = 0;
@@ -391,16 +518,17 @@ Perl_re_intuit_start(pTHX_ REGEXP * const prog, SV *sv, char *strpos,
 #ifdef DEBUGGING
     const char * const i_strpos = strpos;
 #endif
-
     GET_RE_DEBUG_FLAGS_DECL;
 
-    RX_MATCH_UTF8_set(prog,do_utf8);
+    PERL_ARGS_ASSERT_RE_INTUIT_START;
+
+    RX_MATCH_UTF8_set(rx,do_utf8);
 
-    if (prog->extflags & RXf_UTF8) {
+    if (RX_UTF8(rx)) {
        PL_reg_flags |= RF_utf8;
     }
     DEBUG_EXECUTE_r( 
-        debug_start_match(prog, do_utf8, strpos, strend, 
+        debug_start_match(rx, do_utf8, strpos, strend, 
             sv ? "Guessing start of match in sv for"
                : "Guessing start of match in string for");
              );
@@ -501,7 +629,7 @@ Perl_re_intuit_start(pTHX_ REGEXP * const prog, SV *sv, char *strpos,
 #ifdef QDEBUGGING      /* 7/99: reports of failure (with the older version) */
     if (end_shift < 0)
        Perl_croak(aTHX_ "panic: end_shift: %"IVdf" pattern:\n%s\n ",
-                  (IV)end_shift, prog->precomp);
+                  (IV)end_shift, RX_PRECOMP(prog));
 #endif
 
   restart:
@@ -536,7 +664,7 @@ Perl_re_intuit_start(pTHX_ REGEXP * const prog, SV *sv, char *strpos,
        else
            goto fail_finish;
        /* we may be pointing at the wrong string */
-       if (s && RX_MATCH_COPIED(prog))
+       if (s && RXp_MATCH_COPIED(prog))
            s = strbeg + (s - SvPVX_const(sv));
        if (data)
            *data->scream_olds = s;
@@ -853,9 +981,9 @@ Perl_re_intuit_start(pTHX_ REGEXP * const prog, SV *sv, char *strpos,
        {
            /* If flags & SOMETHING - do not do it many times on the same match */
            DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "... Disabling check substring...\n"));
+           /* XXX Does the destruction order has to change with do_utf8? */
            SvREFCNT_dec(do_utf8 ? prog->check_utf8 : prog->check_substr);
-           if (do_utf8 ? prog->check_substr : prog->check_utf8)
-               SvREFCNT_dec(do_utf8 ? prog->check_substr : prog->check_utf8);
+           SvREFCNT_dec(do_utf8 ? prog->check_substr : prog->check_utf8);
            prog->check_substr = prog->check_utf8 = NULL;       /* disable */
            prog->float_substr = prog->float_utf8 = NULL;       /* clear */
            check = NULL;                       /* abort */
@@ -989,24 +1117,41 @@ Perl_re_intuit_start(pTHX_ REGEXP * const prog, SV *sv, char *strpos,
     return NULL;
 }
 
-
+#define DECL_TRIE_TYPE(scan) \
+    const enum { trie_plain, trie_utf8, trie_utf8_fold, trie_latin_utf8_fold } \
+                   trie_type = (scan->flags != EXACT) \
+                             ? (do_utf8 ? trie_utf8_fold : (UTF ? trie_latin_utf8_fold : trie_plain)) \
+                              : (do_utf8 ? trie_utf8 : trie_plain)
 
 #define REXEC_TRIE_READ_CHAR(trie_type, trie, widecharmap, uc, uscan, len,  \
 uvc, charid, foldlen, foldbuf, uniflags) STMT_START {                       \
     switch (trie_type) {                                                    \
     case trie_utf8_fold:                                                    \
        if ( foldlen>0 ) {                                                  \
-           uvc = utf8n_to_uvuni( uscan, UTF8_MAXLEN, &len, uniflags );     \
+           uvc = utf8n_to_uvuni( uscan, UTF8_MAXLEN, &len, uniflags ); \
            foldlen -= len;                                                 \
            uscan += len;                                                   \
            len=0;                                                          \
        } else {                                                            \
-           uvc = utf8n_to_uvuni( (U8*)uc, UTF8_MAXLEN, &len, uniflags );   \
+           uvc = utf8n_to_uvuni( (U8*)uc, UTF8_MAXLEN, &len, uniflags ); \
            uvc = to_uni_fold( uvc, foldbuf, &foldlen );                    \
            foldlen -= UNISKIP( uvc );                                      \
            uscan = foldbuf + UNISKIP( uvc );                               \
        }                                                                   \
        break;                                                              \
+    case trie_latin_utf8_fold:                                              \
+       if ( foldlen>0 ) {                                                  \
+           uvc = utf8n_to_uvuni( uscan, UTF8_MAXLEN, &len, uniflags );     \
+           foldlen -= len;                                                 \
+           uscan += len;                                                   \
+           len=0;                                                          \
+       } else {                                                            \
+           len = 1;                                                        \
+           uvc = to_uni_fold( *(U8*)uc, foldbuf, &foldlen );               \
+           foldlen -= UNISKIP( uvc );                                      \
+           uscan = foldbuf + UNISKIP( uvc );                               \
+       }                                                                   \
+       break;                                                              \
     case trie_utf8:                                                         \
        uvc = utf8n_to_uvuni( (U8*)uc, UTF8_MAXLEN, &len, uniflags );       \
        break;                                                              \
@@ -1014,7 +1159,6 @@ uvc, charid, foldlen, foldbuf, uniflags) STMT_START {                       \
        uvc = (UV)*uc;                                                      \
        len = 1;                                                            \
     }                                                                       \
-                                                                           \
     if (uvc < 256) {                                                        \
        charid = trie->charmap[ uvc ];                                      \
     }                                                                       \
@@ -1029,12 +1173,14 @@ uvc, charid, foldlen, foldbuf, uniflags) STMT_START {                       \
     }                                                                       \
 } STMT_END
 
-#define REXEC_FBC_EXACTISH_CHECK(CoNd)                  \
+#define REXEC_FBC_EXACTISH_CHECK(CoNd)                 \
+{                                                      \
+    char *my_strend= (char *)strend;                   \
     if ( (CoNd)                                        \
         && (ln == len ||                              \
-            ibcmp_utf8(s, NULL, 0,  do_utf8,          \
+            !ibcmp_utf8(s, &my_strend, 0,  do_utf8,   \
                        m, NULL, ln, (bool)UTF))       \
-        && (!reginfo || regtry(reginfo, &s)) )         \
+        && (!reginfo || regtry(reginfo, &s)) )        \
        goto got_it;                                   \
     else {                                             \
         U8 foldbuf[UTF8_MAXBYTES_CASE+1];             \
@@ -1042,15 +1188,14 @@ uvc, charid, foldlen, foldbuf, uniflags) STMT_START {                       \
         f = to_utf8_fold(tmpbuf, foldbuf, &foldlen);  \
         if ( f != c                                   \
              && (f == c1 || f == c2)                  \
-             && (ln == foldlen ||                     \
-                 !ibcmp_utf8((char *) foldbuf,        \
-                             NULL, foldlen, do_utf8,  \
-                             m,                       \
-                             NULL, ln, (bool)UTF))    \
-             && (!reginfo || regtry(reginfo, &s)) )    \
+             && (ln == len ||                         \
+               !ibcmp_utf8(s, &my_strend, 0,  do_utf8,\
+                             m, NULL, ln, (bool)UTF)) \
+             && (!reginfo || regtry(reginfo, &s)) )   \
              goto got_it;                             \
     }                                                  \
-    s += len
+}                                                      \
+s += len
 
 #define REXEC_FBC_EXACTISH_SCAN(CoNd)                     \
 STMT_START {                                              \
@@ -1162,6 +1307,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
        register I32 tmp = 1;   /* Scratch variable? */
        register const bool do_utf8 = PL_reg_match_utf8;
         RXi_GET_DECL(prog,progi);
+
+       PERL_ARGS_ASSERT_FIND_BYCLASS;
         
        /* We know what class it must start with. */
        switch (OP(c)) {
@@ -1209,15 +1356,28 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
                U8 *sm = (U8 *) m;
                U8 tmpbuf1[UTF8_MAXBYTES_CASE+1];
                U8 tmpbuf2[UTF8_MAXBYTES_CASE+1];
-               const U32 uniflags = UTF8_ALLOW_DEFAULT;
-
-               to_utf8_lower((U8*)m, tmpbuf1, &ulen1);
-               to_utf8_upper((U8*)m, tmpbuf2, &ulen2);
-
+               /* used by commented-out code below */
+               /*const U32 uniflags = UTF8_ALLOW_DEFAULT;*/
+               
+                /* XXX: Since the node will be case folded at compile
+                   time this logic is a little odd, although im not 
+                   sure that its actually wrong. --dmq */
+                   
+               c1 = to_utf8_lower((U8*)m, tmpbuf1, &ulen1);
+               c2 = to_utf8_upper((U8*)m, tmpbuf2, &ulen2);
+
+               /* XXX: This is kinda strange. to_utf8_XYZ returns the 
+                   codepoint of the first character in the converted
+                   form, yet originally we did the extra step. 
+                   No tests fail by commenting this code out however
+                   so Ive left it out. -- dmq.
+                   
                c1 = utf8n_to_uvchr(tmpbuf1, UTF8_MAXBYTES_CASE, 
                                    0, uniflags);
                c2 = utf8n_to_uvchr(tmpbuf2, UTF8_MAXBYTES_CASE,
                                    0, uniflags);
+                */
+                
                lnc = 0;
                while (sm < ((U8 *) m + ln)) {
                    lnc++;
@@ -1252,24 +1412,33 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
             * matching (called "loose matching" in Unicode).
             * ibcmp_utf8() will do just that. */
 
-           if (do_utf8) {
+           if (do_utf8 || UTF) {
                UV c, f;
                U8 tmpbuf [UTF8_MAXBYTES+1];
-               STRLEN len, foldlen;
+               STRLEN len = 1;
+               STRLEN foldlen;
                const U32 uniflags = UTF8_ALLOW_DEFAULT;
                if (c1 == c2) {
                    /* Upper and lower of 1st char are equal -
                     * probably not a "letter". */
                    while (s <= e) {
-                       c = utf8n_to_uvchr((U8*)s, UTF8_MAXBYTES, &len,
+                       if (do_utf8) {
+                           c = utf8n_to_uvchr((U8*)s, UTF8_MAXBYTES, &len,
                                           uniflags);
+                        } else {
+                            c = *((U8*)s);
+                        }                                        
                        REXEC_FBC_EXACTISH_CHECK(c == c1);
                    }
                }
                else {
                    while (s <= e) {
-                     c = utf8n_to_uvchr((U8*)s, UTF8_MAXBYTES, &len,
+                       if (do_utf8) {
+                           c = utf8n_to_uvchr((U8*)s, UTF8_MAXBYTES, &len,
                                           uniflags);
+                        } else {
+                            c = *((U8*)s);
+                        }
 
                        /* Handle some of the three Greek sigmas cases.
                         * Note that not all the possible combinations
@@ -1287,6 +1456,7 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
                }
            }
            else {
+               /* Neither pattern nor string are UTF8 */
                if (c1 == c2)
                    REXEC_FBC_EXACTISH_SCAN(*(U8*)s == c1);
                else
@@ -1369,8 +1539,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
            break;
        case ALNUM:
            REXEC_FBC_CSCAN_PRELOAD(
-               LOAD_UTF8_CHARCLASS_ALNUM(),
-               swash_fetch(PL_utf8_alnum, (U8*)s, do_utf8),
+               LOAD_UTF8_CHARCLASS_PERL_WORD(),
+               swash_fetch(RE_utf8_perl_word, (U8*)s, do_utf8),
                isALNUM(*s)
            );
        case ALNUML:
@@ -1380,8 +1550,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
            );
        case NALNUM:
            REXEC_FBC_CSCAN_PRELOAD(
-               LOAD_UTF8_CHARCLASS_ALNUM(),
-               !swash_fetch(PL_utf8_alnum, (U8*)s, do_utf8),
+               LOAD_UTF8_CHARCLASS_PERL_WORD(),
+               !swash_fetch(RE_utf8_perl_word, (U8*)s, do_utf8),
                !isALNUM(*s)
            );
        case NALNUML:
@@ -1391,8 +1561,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
            );
        case SPACE:
            REXEC_FBC_CSCAN_PRELOAD(
-               LOAD_UTF8_CHARCLASS_SPACE(),
-               *s == ' ' || swash_fetch(PL_utf8_space,(U8*)s, do_utf8),
+               LOAD_UTF8_CHARCLASS_PERL_SPACE(),
+               *s == ' ' || swash_fetch(RE_utf8_perl_space,(U8*)s, do_utf8),
                isSPACE(*s)
            );
        case SPACEL:
@@ -1402,8 +1572,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
            );
        case NSPACE:
            REXEC_FBC_CSCAN_PRELOAD(
-               LOAD_UTF8_CHARCLASS_SPACE(),
-               !(*s == ' ' || swash_fetch(PL_utf8_space,(U8*)s, do_utf8)),
+               LOAD_UTF8_CHARCLASS_PERL_SPACE(),
+               !(*s == ' ' || swash_fetch(RE_utf8_perl_space,(U8*)s, do_utf8)),
                !isSPACE(*s)
            );
        case NSPACEL:
@@ -1413,8 +1583,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
            );
        case DIGIT:
            REXEC_FBC_CSCAN_PRELOAD(
-               LOAD_UTF8_CHARCLASS_DIGIT(),
-               swash_fetch(PL_utf8_digit,(U8*)s, do_utf8),
+               LOAD_UTF8_CHARCLASS_POSIX_DIGIT(),
+               swash_fetch(RE_utf8_posix_digit,(U8*)s, do_utf8),
                isDIGIT(*s)
            );
        case DIGITL:
@@ -1424,8 +1594,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
            );
        case NDIGIT:
            REXEC_FBC_CSCAN_PRELOAD(
-               LOAD_UTF8_CHARCLASS_DIGIT(),
-               !swash_fetch(PL_utf8_digit,(U8*)s, do_utf8),
+               LOAD_UTF8_CHARCLASS_POSIX_DIGIT(),
+               !swash_fetch(RE_utf8_posix_digit,(U8*)s, do_utf8),
                !isDIGIT(*s)
            );
        case NDIGITL:
@@ -1461,16 +1631,13 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
        case AHOCORASICKC:
        case AHOCORASICK: 
            {
-               const enum { trie_plain, trie_utf8, trie_utf8_fold }
-                   trie_type = do_utf8 ?
-                         (c->flags == EXACT ? trie_utf8 : trie_utf8_fold)
-                       : trie_plain;
+               DECL_TRIE_TYPE(c);
                 /* what trie are we using right now */
                reg_ac_data *aho
                    = (reg_ac_data*)progi->data->data[ ARG( c ) ];
                reg_trie_data *trie
                    = (reg_trie_data*)progi->data->data[ aho->trie ];
-               HV *widecharmap = (HV*) progi->data->data[ aho->trie + 1 ];
+               HV *widecharmap = MUTABLE_HV(progi->data->data[ aho->trie + 1 ]);
 
                const char *last_start = strend - trie->minlen;
 #ifdef DEBUGGING
@@ -1481,8 +1648,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
                U8 **points; /* map of where we were in the input string
                                when reading a given char. For ASCII this
                                is unnecessary overhead as the relationship
-                               is always 1:1, but for unicode, especially
-                               case folded unicode this is not true. */
+                               is always 1:1, but for Unicode, especially
+                               case folded Unicode this is not true. */
                U8 foldbuf[ UTF8_MAXBYTES_CASE + 1 ];
                U8 *bitmap=NULL;
 
@@ -1680,31 +1847,12 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
        return s;
 }
 
-static void 
-S_swap_match_buff (pTHX_ regexp *prog) {
-    regexp_paren_pair *t;
-
-    if (!prog->swap) {
-    /* We have to be careful. If the previous successful match
-       was from this regex we don't want a subsequent paritally
-       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.
-    */
-        Newxz(prog->swap, (prog->nparens + 1), regexp_paren_pair);
-    }
-    t = prog->swap;
-    prog->swap = prog->offs;
-    prog->offs = t;
-}    
-
 
 /*
  - regexec_flags - match a regexp against a string
  */
 I32
-Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *strend,
+Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, register char *strend,
              char *strbeg, I32 minend, SV *sv, void *data, U32 flags)
 /* strend: pointer to null at end of string */
 /* strbeg: real beginning of string */
@@ -1715,6 +1863,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *st
 /* nosave: For optimizations. */
 {
     dVAR;
+    struct regexp *const prog = (struct regexp *)SvANY(rx);
     /*register*/ char *s;
     register regnode *c;
     /*register*/ char *startpos = stringarg;
@@ -1727,10 +1876,10 @@ Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *st
     I32 multiline;
     RXi_GET_DECL(prog,progi);
     regmatch_info reginfo;  /* create some info to pass to regtry etc */
-    bool swap_on_fail = 0;
-
+    regexp_paren_pair *swap = NULL;
     GET_RE_DEBUG_FLAGS_DECL;
 
+    PERL_ARGS_ASSERT_REGEXEC_FLAGS;
     PERL_UNUSED_ARG(data);
 
     /* Be paranoid... */
@@ -1740,11 +1889,11 @@ Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *st
     }
 
     multiline = prog->extflags & RXf_PMf_MULTILINE;
-    reginfo.prog = prog;
+    reginfo.prog = rx;  /* Yes, sorry that this is confusing.  */
 
-    RX_MATCH_UTF8_set(prog, do_utf8);
+    RX_MATCH_UTF8_set(rx, do_utf8);
     DEBUG_EXECUTE_r( 
-        debug_start_match(prog, do_utf8, startpos, strend, 
+        debug_start_match(rx, do_utf8, startpos, strend, 
         "Matching");
     );
 
@@ -1766,7 +1915,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *st
     PL_reg_eval_set = 0;
     PL_reg_maxiter = 0;
 
-    if (prog->extflags & RXf_UTF8)
+    if (RX_UTF8(rx))
        PL_reg_flags |= RF_utf8;
 
     /* Mark beginning of line for ^ and lookbehind. */
@@ -1785,36 +1934,57 @@ Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *st
 
     if (prog->extflags & RXf_GPOS_SEEN) { /* Need to set reginfo->ganch */
        MAGIC *mg;
-
-       if (flags & REXEC_IGNOREPOS)    /* Means: check only at start */
+       if (flags & REXEC_IGNOREPOS){   /* Means: check only at start */
            reginfo.ganch = startpos + prog->gofs;
-       else if (sv && SvTYPE(sv) >= SVt_PVMG
+           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);
-       } else                          /* pos() not defined */
+            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"));
+       }
     }
-    if (PL_curpm && (PM_GETRE(PL_curpm) == prog)) {
-        swap_on_fail = 1;
-        swap_match_buff(prog); /* do we need a save destructor here for
-                                  eval dies? */
+    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.
+        */
+        swap = prog->offs;
+        /* do we need a save destructor here for eval dies? */
+        Newxz(prog->offs, (prog->nparens + 1), regexp_paren_pair);
     }
     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(prog, sv, s, strend, flags, &d);
+       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 */
@@ -1847,7 +2017,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *st
                    if (s > end)
                        goto phooey;
                    if (prog->extflags & RXf_USE_INTUIT) {
-                       s = re_intuit_start(prog, sv, s + 1, strend, flags, NULL);
+                       s = re_intuit_start(rx, sv, s + 1, strend, flags, NULL);
                        if (!s)
                            goto phooey;
                    }
@@ -1872,7 +2042,8 @@ Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *st
            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 (regtry(&reginfo, &tmp_s))
+
+       if (tmp_s >= strbeg && regtry(&reginfo, &tmp_s))
            goto got_it;
        goto phooey;
     }
@@ -1971,7 +2142,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *st
                                  (unsigned char*)strend, must,
                                  multiline ? FBMrf_MULTILINE : 0))) ) {
            /* we may be pointing at the wrong string */
-           if ((flags & REXEC_SCREAM) && RX_MATCH_COPIED(prog))
+           if ((flags & REXEC_SCREAM) && RXp_MATCH_COPIED(prog))
                s = strbeg + (s - SvPVX_const(sv));
            DEBUG_EXECUTE_r( did_match = 1 );
            if (HOPc(s, -back_max) > last1) {
@@ -2049,7 +2220,7 @@ Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *st
                if (!last)
                    last = scream_olds; /* Only one occurrence. */
                /* we may be pointing at the wrong string */
-               else if (RX_MATCH_COPIED(prog))
+               else if (RXp_MATCH_COPIED(prog))
                    s = strbeg + (s - SvPVX_const(sv));
            }
            else {
@@ -2106,16 +2277,17 @@ Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *st
     goto phooey;
 
 got_it:
-    RX_MATCH_TAINTED_set(prog, PL_reg_flags & RF_tainted);
+    Safefree(swap);
+    RX_MATCH_TAINTED_set(rx, PL_reg_flags & RF_tainted);
 
     if (PL_reg_eval_set)
        restore_pos(aTHX_ prog);
-    if (prog->paren_names
-        (void)hv_iterinit(prog->paren_names);
+    if (RXp_PAREN_NAMES(prog)
+        (void)hv_iterinit(RXp_PAREN_NAMES(prog));
 
     /* make sure $`, $&, $', and $digit will work later */
     if ( !(flags & REXEC_NOT_FIRST) ) {
-       RX_MATCH_COPY_FREE(prog);
+       RX_MATCH_COPY_FREE(rx);
        if (flags & REXEC_COPY_STR) {
            const I32 i = PL_regeol - startpos + (stringarg - strbeg);
 #ifdef PERL_OLD_COPY_ON_WRITE
@@ -2132,7 +2304,7 @@ got_it:
            } else
 #endif
            {
-               RX_MATCH_COPIED_on(prog);
+               RX_MATCH_COPIED_on(rx);
                s = savepvn(strbeg, i);
                prog->subbeg = s;
            }
@@ -2151,10 +2323,12 @@ phooey:
                          PL_colors[4], PL_colors[5]));
     if (PL_reg_eval_set)
        restore_pos(aTHX_ prog);
-    if (swap_on_fail) 
+    if (swap) {
         /* we failed :-( roll it back */
-        swap_match_buff(prog);
-    
+        Safefree(prog->offs);
+        prog->offs = swap;
+    }
+
     return 0;
 }
 
@@ -2167,9 +2341,13 @@ S_regtry(pTHX_ regmatch_info *reginfo, char **startpos)
 {
     dVAR;
     CHECKPOINT lastcp;
-    regexp *prog = reginfo->prog;
+    REGEXP *const rx = reginfo->prog;
+    regexp *const prog = (struct regexp *)SvANY(rx);
     RXi_GET_DECL(prog,progi);
     GET_RE_DEBUG_FLAGS_DECL;
+
+    PERL_ARGS_ASSERT_REGTRY;
+
     reginfo->cutpoint=NULL;
 
     if ((prog->extflags & RXf_EVAL_SEEN) && !PL_reg_eval_set) {
@@ -2192,7 +2370,7 @@ S_regtry(pTHX_ regmatch_info *reginfo, char **startpos)
            /* Make $_ available to executed code. */
            if (reginfo->sv != DEFSV) {
                SAVE_DEFSV;
-               DEFSV = reginfo->sv;
+               DEFSV_set(reginfo->sv);
            }
        
            if (!(SvTYPE(reginfo->sv) >= SVt_PVMG && SvMAGIC(reginfo->sv)
@@ -2214,19 +2392,28 @@ S_regtry(pTHX_ regmatch_info *reginfo, char **startpos)
            Newxz(PL_reg_curpm, 1, PMOP);
 #ifdef USE_ITHREADS
             {
-               SV* const repointer = newSViv(0);
-                /* so we know which PL_regex_padav element is PL_reg_curpm */
-                SvFLAGS(repointer) |= SVf_BREAK;
-                av_push(PL_regex_padav,repointer);
+               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      
         }
-       PM_SETRE(PL_reg_curpm, prog);
+#ifdef USE_ITHREADS
+       /* It seems that non-ithreads works both with and without this code.
+          So for efficiency reasons it seems best not to have the code
+          compiled when it is not needed.  */
+       /* This is safe against NULLs: */
+       ReREFCNT_dec(PM_GETRE(PL_reg_curpm));
+       /* PM_reg_curpm owns a reference to this regexp.  */
+       ReREFCNT_inc(rx);
+#endif
+       PM_SETRE(PL_reg_curpm, rx);
        PL_reg_oldcurpm = PL_curpm;
        PL_curpm = PL_reg_curpm;
-       if (RX_MATCH_COPIED(prog)) {
+       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... */
@@ -2235,7 +2422,7 @@ S_regtry(pTHX_ regmatch_info *reginfo, char **startpos)
 #ifdef PERL_OLD_COPY_ON_WRITE
            PL_nrs = prog->saved_copy;
 #endif
-           RX_MATCH_COPIED_off(prog);
+           RXp_MATCH_COPIED_off(prog);
        }
        else
            PL_reg_oldsaved = NULL;
@@ -2512,15 +2699,18 @@ regmatch(), slabs allocated since entry are freed.
 #ifdef DEBUGGING
 
 STATIC void
-S_debug_start_match(pTHX_ const regexp *prog, const bool do_utf8, 
+S_debug_start_match(pTHX_ const REGEXP *prog, const bool do_utf8, 
     const char *start, const char *end, const char *blurb)
 {
-    const bool utf8_pat= prog->extflags & RXf_UTF8 ? 1 : 0;
+    const bool utf8_pat = RX_UTF8(prog) ? 1 : 0;
+
+    PERL_ARGS_ASSERT_DEBUG_START_MATCH;
+
     if (!PL_colorset)   
             reginitcolors();    
     {
         RE_PV_QUOTED_DECL(s0, utf8_pat, PERL_DEBUG_PAD_ZERO(0), 
-            prog->precomp, prog->prelen, 60);   
+            RX_PRECOMP_const(prog), RX_PRELEN(prog), 60);   
         
         RE_PV_QUOTED_DECL(s1, do_utf8, PERL_DEBUG_PAD_ZERO(1), 
             start, end - start, 60); 
@@ -2559,6 +2749,8 @@ S_dump_exec_pos(pTHX_ const char *locinput,
        ? (5 + taill) - l : locinput - loc_bostr;
     int pref0_len;
 
+    PERL_ARGS_ASSERT_DUMP_EXEC_POS;
+
     while (do_utf8 && UTF8_IS_CONTINUATION(*(U8*)(locinput - pref_len)))
        pref_len++;
     pref0_len = pref_len  - (locinput - loc_reg_starttry);
@@ -2609,11 +2801,15 @@ S_dump_exec_pos(pTHX_ const char *locinput,
  * or 0 if non of the buffers matched.
  */
 STATIC I32
-S_reg_check_named_buff_matched(pTHX_ const regexp *rex, const regnode *scan) {
+S_reg_check_named_buff_matched(pTHX_ const regexp *rex, const regnode *scan)
+{
     I32 n;
     RXi_GET_DECL(rex,rexi);
-    SV *sv_dat=(SV*)rexi->data->data[ ARG( scan ) ];
+    SV *sv_dat= MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
     I32 *nums=(I32*)SvPVX(sv_dat);
+
+    PERL_ARGS_ASSERT_REG_CHECK_NAMED_BUFF_MATCHED;
+
     for ( n=0; n<SvIVX(sv_dat); n++ ) {
         if ((I32)*PL_reglastparen >= nums[n] &&
             PL_regoffs[nums[n]].end != -1)
@@ -2657,15 +2853,12 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
     dVAR;
     register const bool do_utf8 = PL_reg_match_utf8;
     const U32 uniflags = UTF8_ALLOW_DEFAULT;
-
-    regexp *rex = reginfo->prog;
+    REGEXP *rex_sv = reginfo->prog;
+    regexp *rex = (struct regexp *)SvANY(rex_sv);
     RXi_GET_DECL(rex,rexi);
-    
     I32        oldsave;
-
     /* the current state. This is a cached copy of PL_regmatch_state */
     register regmatch_state *st;
-
     /* cache heavy used fields of st in registers */
     register regnode *scan;
     register regnode *next;
@@ -2680,13 +2873,11 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
     const U32 max_nochange_depth =
         (3 * rex->nparens > MAX_RECURSE_EVAL_NOCHANGE_DEPTH) ?
         3 * rex->nparens : MAX_RECURSE_EVAL_NOCHANGE_DEPTH;
-            
     regmatch_state *yes_state = NULL; /* state to pop to on success of
                                                            subpattern */
     /* mark_state piggy backs on the yes_state logic so that when we unwind 
        the stack on success we can update the mark_state as we go */
     regmatch_state *mark_state = NULL; /* last mark state we have seen */
-    
     regmatch_state *cur_eval = NULL; /* most recent EVAL_AB state */
     struct regmatch_state  *cur_curlyx = NULL; /* most recent curlyx */
     U32 state_num;
@@ -2699,10 +2890,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                                during a successfull match */
     U32 lastopen = 0;       /* last open we saw */
     bool has_cutgroup = RX_HAS_CUTGROUP(rex) ? 1 : 0;   
-
     SV* const oreplsv = GvSV(PL_replgv);
-               
-    
     /* these three flags are set by various ops to signal information to
      * the very next op. They have a useful lifetime of exactly one loop
      * iteration, and are not preserved or restored by state pushes/pops
@@ -2717,11 +2905,12 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                                false: plain (?=foo)
                                true:  used as a condition: (?(?=foo))
                            */
-
 #ifdef DEBUGGING
     GET_RE_DEBUG_FLAGS_DECL;
 #endif
 
+    PERL_ARGS_ASSERT_REGMATCH;
+
     DEBUG_OPTIMISE_r( DEBUG_EXECUTE_r({
            PerlIO_printf(Perl_debug_log,"regmatch start\n");
     }));
@@ -2768,6 +2957,11 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
        state_num = OP(scan);
 
       reenter_switch:
+
+       assert(PL_reglastparen == &rex->lastparen);
+       assert(PL_reglastcloseparen == &rex->lastcloseparen);
+       assert(PL_regoffs == rex->offs);
+
        switch (state_num) {
        case BOL:
            if (locinput == PL_bostr)
@@ -2872,15 +3066,12 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
        case TRIE:
            {
                 /* what type of TRIE am I? (utf8 makes this contextual) */
-               const enum { trie_plain, trie_utf8, trie_utf8_fold }
-                   trie_type = do_utf8 ?
-                         (scan->flags == EXACT ? trie_utf8 : trie_utf8_fold)
-                       : trie_plain;
+                DECL_TRIE_TYPE(scan);
 
                 /* what trie are we using right now */
                reg_trie_data * const trie
                    = (reg_trie_data*)rexi->data->data[ ARG( scan ) ];
-               HV * widecharmap = (HV *)rexi->data->data[ ARG( scan ) + 1 ];
+               HV * widecharmap = MUTABLE_HV(rexi->data->data[ ARG( scan ) + 1 ]);
                 U32 state = trie->startstate;
 
                if (trie->bitmap && trie_type != trie_utf8_fold &&
@@ -2937,7 +3128,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                    if ( got_wordnum ) {
                        if ( ! ST.accepted ) {
                            ENTER;
-                           SAVETMPS;
+                           SAVETMPS; /* XXX is this necessary? dmq */
                            bufflen = TRIE_INITAL_ACCEPT_BUFFLEN;
                            sv_accept_buff=newSV(bufflen *
                                            sizeof(reg_trie_accepted) - 1);
@@ -3037,7 +3228,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                /* only one choice left - just continue */
                DEBUG_EXECUTE_r({
                    AV *const trie_words
-                       = (AV *) rexi->data->data[ARG(ST.me)+TRIE_WORDS_OFFSET];
+                       = MUTABLE_AV(rexi->data->data[ARG(ST.me)+TRIE_WORDS_OFFSET]);
                    SV ** const tmp = av_fetch( trie_words, 
                        ST.accept_buff[ 0 ].wordnum-1, 0 );
                    SV *sv= tmp ? sv_newmortal() : NULL;
@@ -3119,7 +3310,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
 
                DEBUG_EXECUTE_r({
                    AV *const trie_words
-                       = (AV *) rexi->data->data[ARG(ST.me)+TRIE_WORDS_OFFSET];
+                       = MUTABLE_AV(rexi->data->data[ARG(ST.me)+TRIE_WORDS_OFFSET]);
                    SV ** const tmp = av_fetch( trie_words, 
                        ST.accept_buff[ best ].wordnum - 1, 0 );
                    regnode *nextop=(!ST.jump || !ST.jump[ST.accept_buff[best].wordnum]) ? 
@@ -3148,22 +3339,17 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                PL_reginput = (char *)ST.accept_buff[ best ].endpos;
                if ( !ST.jump || !ST.jump[ST.accept_buff[best].wordnum]) {
                    scan = ST.B;
-                   /* NOTREACHED */
                } else {
                    scan = ST.me + ST.jump[ST.accept_buff[best].wordnum];
-                   /* NOTREACHED */
-                }
-                if (has_cutgroup) {
-                    PUSH_YES_STATE_GOTO(TRIE_next, scan);    
-                    /* NOTREACHED */
-                } else {
-                    PUSH_STATE_GOTO(TRIE_next, scan);
-                    /* NOTREACHED */
                 }
+                PUSH_YES_STATE_GOTO(TRIE_next, scan);    
                 /* NOTREACHED */
            }
            /* NOTREACHED */
         case TRIE_next:
+           /* we dont want to throw this away, see bug 57042*/
+           if (oreplsv != GvSV(PL_replgv))
+               sv_setsv(oreplsv, GvSV(PL_replgv));
             FREETMPS;
            LEAVE;
            sayYES;
@@ -3271,85 +3457,6 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
            nextchr = UCHARAT(locinput);
            break;
            }
-       case ANYOF:
-           if (do_utf8) {
-               STRLEN inclasslen = PL_regeol - locinput;
-
-               if (!reginclass(rex, scan, (U8*)locinput, &inclasslen, do_utf8))
-                   goto anyof_fail;
-               if (locinput >= PL_regeol)
-                   sayNO;
-               locinput += inclasslen ? inclasslen : UTF8SKIP(locinput);
-               nextchr = UCHARAT(locinput);
-               break;
-           }
-           else {
-               if (nextchr < 0)
-                   nextchr = UCHARAT(locinput);
-               if (!REGINCLASS(rex, scan, (U8*)locinput))
-                   goto anyof_fail;
-               if (!nextchr && locinput >= PL_regeol)
-                   sayNO;
-               nextchr = UCHARAT(++locinput);
-               break;
-           }
-       anyof_fail:
-           /* If we might have the case of the German sharp s
-            * in a casefolding Unicode character class. */
-
-           if (ANYOF_FOLD_SHARP_S(scan, locinput, PL_regeol)) {
-                locinput += SHARP_S_SKIP;
-                nextchr = UCHARAT(locinput);
-           }
-           else
-                sayNO;
-           break;
-       case ALNUML:
-           PL_reg_flags |= RF_tainted;
-           /* FALL THROUGH */
-       case ALNUM:
-           if (!nextchr)
-               sayNO;
-           if (do_utf8) {
-               LOAD_UTF8_CHARCLASS_ALNUM();
-               if (!(OP(scan) == ALNUM
-                     ? (bool)swash_fetch(PL_utf8_alnum, (U8*)locinput, do_utf8)
-                     : isALNUM_LC_utf8((U8*)locinput)))
-               {
-                   sayNO;
-               }
-               locinput += PL_utf8skip[nextchr];
-               nextchr = UCHARAT(locinput);
-               break;
-           }
-           if (!(OP(scan) == ALNUM
-                 ? isALNUM(nextchr) : isALNUM_LC(nextchr)))
-               sayNO;
-           nextchr = UCHARAT(++locinput);
-           break;
-       case NALNUML:
-           PL_reg_flags |= RF_tainted;
-           /* FALL THROUGH */
-       case NALNUM:
-           if (!nextchr && locinput >= PL_regeol)
-               sayNO;
-           if (do_utf8) {
-               LOAD_UTF8_CHARCLASS_ALNUM();
-               if (OP(scan) == NALNUM
-                   ? (bool)swash_fetch(PL_utf8_alnum, (U8*)locinput, do_utf8)
-                   : isALNUM_LC_utf8((U8*)locinput))
-               {
-                   sayNO;
-               }
-               locinput += PL_utf8skip[nextchr];
-               nextchr = UCHARAT(locinput);
-               break;
-           }
-           if (OP(scan) == NALNUM
-               ? isALNUM(nextchr) : isALNUM_LC(nextchr))
-               sayNO;
-           nextchr = UCHARAT(++locinput);
-           break;
        case BOUNDL:
        case NBOUNDL:
            PL_reg_flags |= RF_tainted;
@@ -3362,7 +3469,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                    ln = '\n';
                else {
                    const U8 * const r = reghop3((U8*)locinput, -1, (U8*)PL_bostr);
-               
+
                    ln = utf8n_to_uvchr(r, UTF8SKIP(r), 0, uniflags);
                }
                if (OP(scan) == BOUND || OP(scan) == NBOUND) {
@@ -3391,122 +3498,259 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                                    OP(scan) == BOUNDL))
                    sayNO;
            break;
-       case SPACEL:
-           PL_reg_flags |= RF_tainted;
-           /* FALL THROUGH */
-       case SPACE:
-           if (!nextchr)
-               sayNO;
+       case ANYOF:
            if (do_utf8) {
-               if (UTF8_IS_CONTINUED(nextchr)) {
-                   LOAD_UTF8_CHARCLASS_SPACE();
-                   if (!(OP(scan) == SPACE
-                         ? (bool)swash_fetch(PL_utf8_space, (U8*)locinput, do_utf8)
-                         : isSPACE_LC_utf8((U8*)locinput)))
-                   {
-                       sayNO;
-                   }
-                   locinput += PL_utf8skip[nextchr];
-                   nextchr = UCHARAT(locinput);
-                   break;
-               }
-               if (!(OP(scan) == SPACE
-                     ? isSPACE(nextchr) : isSPACE_LC(nextchr)))
+               STRLEN inclasslen = PL_regeol - locinput;
+
+               if (!reginclass(rex, scan, (U8*)locinput, &inclasslen, do_utf8))
+                   goto anyof_fail;
+               if (locinput >= PL_regeol)
                    sayNO;
-               nextchr = UCHARAT(++locinput);
+               locinput += inclasslen ? inclasslen : UTF8SKIP(locinput);
+               nextchr = UCHARAT(locinput);
+               break;
            }
            else {
-               if (!(OP(scan) == SPACE
-                     ? isSPACE(nextchr) : isSPACE_LC(nextchr)))
+               if (nextchr < 0)
+                   nextchr = UCHARAT(locinput);
+               if (!REGINCLASS(rex, scan, (U8*)locinput))
+                   goto anyof_fail;
+               if (!nextchr && locinput >= PL_regeol)
                    sayNO;
                nextchr = UCHARAT(++locinput);
-           }
-           break;
-       case NSPACEL:
-           PL_reg_flags |= RF_tainted;
-           /* FALL THROUGH */
-       case NSPACE:
-           if (!nextchr && locinput >= PL_regeol)
-               sayNO;
-           if (do_utf8) {
-               LOAD_UTF8_CHARCLASS_SPACE();
-               if (OP(scan) == NSPACE
-                   ? (bool)swash_fetch(PL_utf8_space, (U8*)locinput, do_utf8)
-                   : isSPACE_LC_utf8((U8*)locinput))
-               {
-                   sayNO;
-               }
-               locinput += PL_utf8skip[nextchr];
-               nextchr = UCHARAT(locinput);
                break;
            }
-           if (OP(scan) == NSPACE
-               ? isSPACE(nextchr) : isSPACE_LC(nextchr))
-               sayNO;
-           nextchr = UCHARAT(++locinput);
-           break;
-       case DIGITL:
-           PL_reg_flags |= RF_tainted;
-           /* FALL THROUGH */
-       case DIGIT:
-           if (!nextchr)
-               sayNO;
-           if (do_utf8) {
-               LOAD_UTF8_CHARCLASS_DIGIT();
-               if (!(OP(scan) == DIGIT
-                     ? (bool)swash_fetch(PL_utf8_digit, (U8*)locinput, do_utf8)
-                     : isDIGIT_LC_utf8((U8*)locinput)))
-               {
-                   sayNO;
-               }
-               locinput += PL_utf8skip[nextchr];
-               nextchr = UCHARAT(locinput);
-               break;
+       anyof_fail:
+           /* If we might have the case of the German sharp s
+            * in a casefolding Unicode character class. */
+
+           if (ANYOF_FOLD_SHARP_S(scan, locinput, PL_regeol)) {
+                locinput += SHARP_S_SKIP;
+                nextchr = UCHARAT(locinput);
            }
-           if (!(OP(scan) == DIGIT
-                 ? isDIGIT(nextchr) : isDIGIT_LC(nextchr)))
-               sayNO;
-           nextchr = UCHARAT(++locinput);
+           else
+                sayNO;
            break;
-       case NDIGITL:
-           PL_reg_flags |= RF_tainted;
-           /* FALL THROUGH */
-       case NDIGIT:
-           if (!nextchr && locinput >= PL_regeol)
+       /* Special char classes - The defines start on line 129 or so */
+       CCC_TRY_AFF( ALNUM,  ALNUML, perl_word,   "a", isALNUM_LC_utf8, isALNUM, isALNUM_LC);
+       CCC_TRY_NEG(NALNUM, NALNUML, perl_word,   "a", isALNUM_LC_utf8, isALNUM, isALNUM_LC);
+
+       CCC_TRY_AFF( SPACE,  SPACEL, perl_space,  " ", isSPACE_LC_utf8, isSPACE, isSPACE_LC);
+       CCC_TRY_NEG(NSPACE, NSPACEL, perl_space,  " ", isSPACE_LC_utf8, isSPACE, isSPACE_LC);
+
+       CCC_TRY_AFF( DIGIT,  DIGITL, posix_digit, "0", isDIGIT_LC_utf8, isDIGIT, isDIGIT_LC);
+       CCC_TRY_NEG(NDIGIT, NDIGITL, posix_digit, "0", isDIGIT_LC_utf8, isDIGIT, isDIGIT_LC);
+
+       case CLUMP: /* Match \X: logical Unicode character.  This is defined as
+                      a Unicode extended Grapheme Cluster */
+           /* From http://www.unicode.org/reports/tr29 (5.2 version).  An
+             extended Grapheme Cluster is:
+
+              CR LF
+              | Prepend* Begin Extend*
+              | .
+
+              Begin is (Hangul-syllable | ! Control)
+              Extend is (Grapheme_Extend | Spacing_Mark)
+              Control is [ GCB_Control CR LF ]
+
+              The discussion below shows how the code for CLUMP is derived
+              from this regex.  Note that most of these concepts are from
+              property values of the Grapheme Cluster Boundary (GCB) property.
+              No code point can have multiple property values for a given
+              property.  Thus a code point in Prepend can't be in Control, but
+              it must be in !Control.  This is why Control above includes
+              GCB_Control plus CR plus LF.  The latter two are used in the GCB
+              property separately, and so can't be in GCB_Control, even though
+              they logically are controls.  Control is not the same as gc=cc,
+              but includes format and other characters as well.
+
+              The Unicode definition of Hangul-syllable is:
+                  L+
+                  | (L* ( ( V | LV ) V* | LVT ) T*)
+                  | T+ 
+                 )
+              Each of these is a value for the GCB property, and hence must be
+              disjoint, so the order they are tested is immaterial, so the
+              above can safely be changed to
+                  T+
+                  | L+
+                  | (L* ( LVT | ( V | LV ) V*) T*)
+
+              The last two terms can be combined like this:
+                  L* ( L
+                       | (( LVT | ( V | LV ) V*) T*))
+
+              And refactored into this:
+                  L* (L | LVT T* | V  V* T* | LV  V* T*)
+
+              That means that if we have seen any L's at all we can quit
+              there, but if the next character is a LVT, a V or and LV we
+              should keep going.
+
+              There is a subtlety with Prepend* which showed up in testing.
+              Note that the Begin, and only the Begin is required in:
+               | Prepend* Begin Extend*
+              Also, Begin contains '! Control'.  A Prepend must be a '!
+              Control', which means it must be a Begin.  What it comes down to
+              is that if we match Prepend* and then find no suitable Begin
+              afterwards, that if we backtrack the last Prepend, that one will
+              be a suitable Begin.
+           */
+
+           if (locinput >= PL_regeol)
                sayNO;
-           if (do_utf8) {
-               LOAD_UTF8_CHARCLASS_DIGIT();
-               if (OP(scan) == NDIGIT
-                   ? (bool)swash_fetch(PL_utf8_digit, (U8*)locinput, do_utf8)
-                   : isDIGIT_LC_utf8((U8*)locinput))
-               {
-                   sayNO;
+           if  (! do_utf8) {
+
+               /* Match either CR LF  or '.', as all the other possibilities
+                * require utf8 */
+               locinput++;         /* Match the . or CR */
+               if (nextchr == '\r'
+                   && locinput < PL_regeol
+                   && UCHARAT(locinput) == '\n') locinput++;
+           }
+           else {
+
+               /* Utf8: See if is ( CR LF ); already know that locinput <
+                * PL_regeol, so locinput+1 is in bounds */
+               if (nextchr == '\r' && UCHARAT(locinput + 1) == '\n') {
+                   locinput += 2;
                }
-               locinput += PL_utf8skip[nextchr];
-               nextchr = UCHARAT(locinput);
-               break;
+               else {
+                   /* In case have to backtrack to beginning, then match '.' */
+                   char *starting = locinput;
+
+                   /* In case have to backtrack the last prepend */
+                   char *previous_prepend = 0;
+
+                   LOAD_UTF8_CHARCLASS_GCB();
+
+                   /* Match (prepend)* */
+                   while (locinput < PL_regeol
+                          && swash_fetch(PL_utf8_X_prepend,
+                                         (U8*)locinput, do_utf8))
+                   {
+                       previous_prepend = locinput;
+                       locinput += UTF8SKIP(locinput);
+                   }
+
+                   /* As noted above, if we matched a prepend character, but
+                    * 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
+                           || ! swash_fetch(PL_utf8_X_begin,
+                                            (U8*)locinput, do_utf8)))
+                   {
+                       locinput = previous_prepend;
+                   }
+
+                   /* Note that here we know PL_regeol > 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
+                    * now pass */
+                   if (! swash_fetch(PL_utf8_X_begin, (U8*)locinput, do_utf8)) {
+
+                       /* Here did not match the required 'Begin' in the
+                        * second term.  So just match the very first
+                        * character, the '.' of the final term of the regex */
+                       locinput = starting + UTF8SKIP(starting);
+                   } else {
+
+                       /* Here is the beginning of a character that can have
+                        * an extender.  It is either a hangul syllable, or a
+                        * non-control */
+                       if (swash_fetch(PL_utf8_X_non_hangul,
+                                       (U8*)locinput, do_utf8))
+                       {
+
+                           /* Here not a Hangul syllable, must be a
+                            * ('!  * Control') */
+                           locinput += UTF8SKIP(locinput);
+                       } else {
+
+                           /* Here is a Hangul syllable.  It can be composed
+                            * of several individual characters.  One
+                            * possibility is T+ */
+                           if (swash_fetch(PL_utf8_X_T,
+                                           (U8*)locinput, do_utf8))
+                           {
+                               while (locinput < PL_regeol
+                                       && swash_fetch(PL_utf8_X_T,
+                                                       (U8*)locinput, do_utf8))
+                               {
+                                   locinput += UTF8SKIP(locinput);
+                               }
+                           } else {
+
+                               /* Here, not T+, but is a Hangul.  That means
+                                * it is one of the others: L, LV, LVT or V,
+                                * and matches:
+                                * L* (L | LVT T* | V  V* T* | LV  V* T*) */
+
+                               /* Match L*           */
+                               while (locinput < PL_regeol
+                                       && swash_fetch(PL_utf8_X_L,
+                                                       (U8*)locinput, do_utf8))
+                               {
+                                   locinput += UTF8SKIP(locinput);
+                               }
+
+                               /* Here, have exhausted L*.  If the next
+                                * character is not an LV, LVT nor V, it means
+                                * we had to have at least one L, so matches L+
+                                * in the original equation, we have a complete
+                                * hangul syllable.  Are done. */
+
+                               if (locinput < PL_regeol
+                                   && swash_fetch(PL_utf8_X_LV_LVT_V,
+                                                   (U8*)locinput, do_utf8))
+                               {
+
+                                   /* Otherwise keep going.  Must be LV, LVT
+                                    * or V.  See if LVT */
+                                   if (swash_fetch(PL_utf8_X_LVT,
+                                                   (U8*)locinput, do_utf8))
+                                   {
+                                       locinput += UTF8SKIP(locinput);
+                                   } else {
+
+                                       /* Must be  V or LV.  Take it, then
+                                        * match V*     */
+                                       locinput += UTF8SKIP(locinput);
+                                       while (locinput < PL_regeol
+                                               && swash_fetch(PL_utf8_X_V,
+                                                        (U8*)locinput, do_utf8))
+                                       {
+                                           locinput += UTF8SKIP(locinput);
+                                       }
+                                   }
+
+                                   /* And any of LV, LVT, or V can be followed
+                                    * by T*            */
+                                   while (locinput < PL_regeol
+                                          && swash_fetch(PL_utf8_X_T,
+                                                          (U8*)locinput,
+                                                          do_utf8))
+                                   {
+                                       locinput += UTF8SKIP(locinput);
+                                   }
+                               }
+                           }
+                       }
+
+                       /* Match any extender */
+                       while (locinput < PL_regeol
+                               && swash_fetch(PL_utf8_X_extend,
+                                               (U8*)locinput, do_utf8))
+                       {
+                           locinput += UTF8SKIP(locinput);
+                       }
+                   }
+               }
+               if (locinput > PL_regeol) sayNO;
            }
-           if (OP(scan) == NDIGIT
-               ? isDIGIT(nextchr) : isDIGIT_LC(nextchr))
-               sayNO;
-           nextchr = UCHARAT(++locinput);
-           break;
-       case CLUMP:
-           if (locinput >= PL_regeol)
-               sayNO;
-           if  (do_utf8) {
-               LOAD_UTF8_CHARCLASS_MARK();
-               if (swash_fetch(PL_utf8_mark,(U8*)locinput, do_utf8))
-                   sayNO;
-               locinput += PL_utf8skip[nextchr];
-               while (locinput < PL_regeol &&
-                      swash_fetch(PL_utf8_mark,(U8*)locinput, do_utf8))
-                   locinput += UTF8SKIP(locinput);
-               if (locinput > PL_regeol)
-                   sayNO;
-           } 
-           else
-              locinput++;
            nextchr = UCHARAT(locinput);
            break;
             
@@ -3602,6 +3846,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
 #define ST st->u.eval
        {
            SV *ret;
+           REGEXP *re_sv;
             regexp *re;
             regexp_internal *rei;
             regnode *startpoint;
@@ -3618,9 +3863,10 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
             } else {
                 nochange_depth = 0;
             }
+           re_sv = rex_sv;
             re = rex;
             rei = rexi;
-            (void)ReREFCNT_inc(rex);
+            (void)ReREFCNT_inc(rex_sv);
             if (OP(scan)==GOSUB) {
                 startpoint = scan + ARG2L(scan);
                 ST.close_paren = ARG(scan);
@@ -3644,6 +3890,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                OP_4tree * const oop = PL_op;
                COP * const ocurcop = PL_curcop;
                PAD *old_comppad;
+               char *saved_regeol = PL_regeol;
            
                n = ARG(scan);
                PL_op = (OP_4tree*)rexi->data->data[n];
@@ -3669,6 +3916,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                PL_op = oop;
                PAD_RESTORE_LOCAL(old_comppad);
                PL_curcop = ocurcop;
+               PL_regeol = saved_regeol;
                if (!logical) {
                    /* /(?{...})/ */
                    sv_setsv(save_scalar(PL_replgv), ret);
@@ -3680,41 +3928,80 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                {
                    /* extract RE object from returned value; compiling if
                     * necessary */
-
                    MAGIC *mg = NULL;
-                   const SV *sv;
-                   if(SvROK(ret) && SvSMAGICAL(sv = SvRV(ret)))
-                       mg = mg_find(sv, PERL_MAGIC_qr);
-                   else if (SvSMAGICAL(ret)) {
-                       if (SvGMAGICAL(ret))
+                   REGEXP *rx = NULL;
+
+                   if (SvROK(ret)) {
+                       SV *const sv = SvRV(ret);
+
+                       if (SvTYPE(sv) == SVt_REGEXP) {
+                           rx = (REGEXP*) sv;
+                       } else if (SvSMAGICAL(sv)) {
+                           mg = mg_find(sv, PERL_MAGIC_qr);
+                           assert(mg);
+                       }
+                   } else if (SvTYPE(ret) == SVt_REGEXP) {
+                       rx = (REGEXP*) ret;
+                   } else if (SvSMAGICAL(ret)) {
+                       if (SvGMAGICAL(ret)) {
+                           /* I don't believe that there is ever qr magic
+                              here.  */
+                           assert(!mg_find(ret, PERL_MAGIC_qr));
                            sv_unmagic(ret, PERL_MAGIC_qr);
-                       else
+                       }
+                       else {
                            mg = mg_find(ret, PERL_MAGIC_qr);
+                           /* testing suggests mg only ends up non-NULL for
+                              scalars who were upgraded and compiled in the
+                              else block below. In turn, this is only
+                              triggered in the "postponed utf8 string" tests
+                              in t/op/pat.t  */
+                       }
                    }
 
                    if (mg) {
-                       re = reg_temp_copy((regexp *)mg->mg_obj); /*XXX:dmq*/
+                       rx = (REGEXP *) mg->mg_obj; /*XXX:dmq*/
+                       assert(rx);
+                   }
+                   if (rx) {
+                       rx = reg_temp_copy(NULL, rx);
                    }
                    else {
                        U32 pm_flags = 0;
                        const I32 osize = PL_regsize;
 
-                       if (DO_UTF8(ret)) pm_flags |= RXf_UTF8;
-                       re = CALLREGCOMP(ret, pm_flags);
+                       if (DO_UTF8(ret)) {
+                           assert (SvUTF8(ret));
+                       } else if (SvUTF8(ret)) {
+                           /* Not doing UTF-8, despite what the SV says. Is
+                              this only if we're trapped in use 'bytes'?  */
+                           /* Make a copy of the octet sequence, but without
+                              the flag on, as the compiler now honours the
+                              SvUTF8 flag on ret.  */
+                           STRLEN len;
+                           const char *const p = SvPV(ret, len);
+                           ret = newSVpvn_flags(p, len, SVs_TEMP);
+                       }
+                       rx = CALLREGCOMP(ret, pm_flags);
                        if (!(SvFLAGS(ret)
                              & (SVs_TEMP | SVs_PADTMP | SVf_READONLY
-                               | SVs_GMG)))
-                           sv_magic(ret,(SV*)ReREFCNT_inc(re),
-                                       PERL_MAGIC_qr,0,0);
+                                | SVs_GMG))) {
+                           /* This isn't a first class regexp. Instead, it's
+                              caching a regexp onto an existing, Perl visible
+                              scalar.  */
+                           sv_magic(ret, MUTABLE_SV(rx), PERL_MAGIC_qr, 0, 0);
+                       }
                        PL_regsize = osize;
                    }
+                   re_sv = rx;
+                   re = (struct regexp *)SvANY(rx);
                }
-                RX_MATCH_COPIED_off(re);
+                RXp_MATCH_COPIED_off(re);
                 re->subbeg = rex->subbeg;
                 re->sublen = rex->sublen;
                rei = RXi_GET(re);
                 DEBUG_EXECUTE_r(
-                    debug_start_match(re, do_utf8, locinput, PL_regeol, 
+                    debug_start_match(re_sv, do_utf8, locinput, PL_regeol, 
                         "Matching embedded");
                );              
                startpoint = rei->program + 1;
@@ -3735,8 +4022,12 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                
                PL_regoffs = re->offs; /* essentially NOOP on GOSUB */
                
-               *PL_reglastparen = 0;
-               *PL_reglastcloseparen = 0;
+               /* see regtry, specifically PL_reglast(?:close)?paren is a pointer! (i dont know why) :dmq */
+               PL_reglastparen = &re->lastparen;
+               PL_reglastcloseparen = &re->lastcloseparen;
+               re->lastparen = 0;
+               re->lastcloseparen = 0;
+
                PL_reginput = locinput;
                PL_regsize = 0;
 
@@ -3744,15 +4035,16 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                PL_reg_maxiter = 0;
 
                ST.toggle_reg_flags = PL_reg_flags;
-               if (re->extflags & RXf_UTF8)
+               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 */
 
-               ST.prev_rex = rex;
+               ST.prev_rex = rex_sv;
                ST.prev_curlyx = cur_curlyx;
-               SETREX(rex,re);
+               SETREX(rex_sv,re_sv);
+               rex = re;
                rexi = rei;
                cur_curlyx = NULL;
                ST.B = next;
@@ -3771,12 +4063,20 @@ S_regmatch(pTHX_ regmatch_info *reginfo, 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; 
-           ReREFCNT_dec(rex);
-           SETREX(rex,ST.prev_rex);
+           ReREFCNT_dec(rex_sv);
+           SETREX(rex_sv,ST.prev_rex);
+           rex = (struct regexp *)SvANY(rex_sv);
            rexi = RXi_GET(rex);
            regcpblow(ST.cp);
            cur_eval = ST.prev_eval;
            cur_curlyx = ST.prev_curlyx;
+
+           /* rex was changed so update the pointer in PL_reglastparen and PL_reglastcloseparen */
+           PL_reglastparen = &rex->lastparen;
+           PL_reglastcloseparen = &rex->lastcloseparen;
+           /* also update PL_regoffs */
+           PL_regoffs = rex->offs;
+           
            /* XXXX This is too dramatic a measure... */
            PL_reg_maxiter = 0;
             if ( nochange_depth )
@@ -3787,9 +4087,14 @@ S_regmatch(pTHX_ regmatch_info *reginfo, 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; 
-           ReREFCNT_dec(rex);
-           SETREX(rex,ST.prev_rex);
+           ReREFCNT_dec(rex_sv);
+           SETREX(rex_sv,ST.prev_rex);
+           rex = (struct regexp *)SvANY(rex_sv);
            rexi = RXi_GET(rex); 
+           /* rex was changed so update the pointer in PL_reglastparen and PL_reglastcloseparen */
+           PL_reglastparen = &rex->lastparen;
+           PL_reglastcloseparen = &rex->lastcloseparen;
+
            PL_reginput = locinput;
            REGCP_UNWIND(ST.lastcp);
            regcppop(rex);
@@ -4219,12 +4524,6 @@ NULL
 
        case BRANCH:        /*  /(...|A|...)/ */
            scan = NEXTOPER(scan); /* scan now points to inner node */
-           if ((!next || (OP(next) != BRANCH && OP(next) != BRANCHJ)) 
-               && !has_cutgroup)
-           {
-               /* last branch; skip state push and jump direct to node */
-               continue;
-            }
            ST.lastparen = *PL_reglastparen;
            ST.next_branch = next;
            REGCP_SET(ST.cp);
@@ -4240,7 +4539,7 @@ NULL
         case CUTGROUP:
             PL_reginput = locinput;
             sv_yes_mark = st->u.mark.mark_name = scan->flags ? NULL :
-                (SV*)rexi->data->data[ ARG( scan ) ];
+                MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
             PUSH_STATE_GOTO(CUTGROUP_next,next);
             /* NOTREACHED */
         case CUTGROUP_next_fail:
@@ -4288,7 +4587,7 @@ NULL
        case CURLYM:    /* /A{m,n}B/ where A is fixed-length */
 
            /* This is an optimisation of CURLYX that enables us to push
-            * only a single backtracking state, no matter now many matches
+            * only a single backtracking state, no matter how many matches
             * there are in {m,n}. It relies on the pattern being constant
             * length, with no parens to influence future backrefs
             */
@@ -4355,8 +4654,11 @@ NULL
                cur_eval->u.eval.close_paren == (U32)ST.me->flags) 
                goto fake_end;
                
-           if ( ST.count < (ST.minmod ? ARG1(ST.me) : ARG2(ST.me)) )
-               goto curlym_do_A; /* try to match another A */
+           {
+               I32 max = (ST.minmod ? ARG1(ST.me) : ARG2(ST.me));
+               if ( max == REG_INFTY || ST.count < max )
+                   goto curlym_do_A; /* try to match another A */
+           }
            goto curlym_do_B; /* try to match B */
 
        case CURLYM_A_fail: /* just failed to match an A */
@@ -4448,7 +4750,8 @@ NULL
        case CURLYM_B_fail: /* just failed to match a B */
            REGCP_UNWIND(ST.cp);
            if (ST.minmod) {
-               if (ST.count == ARG2(ST.me) /* max */)
+               I32 max = ARG2(ST.me);
+               if (max != REG_INFTY && ST.count == max)
                    sayNO;
                goto curlym_do_A; /* try to match a further A */
            }
@@ -4788,12 +5091,18 @@ NULL
                            = cur_eval->u.eval.toggle_reg_flags;
                PL_reg_flags ^= st->u.eval.toggle_reg_flags; 
 
-               st->u.eval.prev_rex = rex;              /* inner */
-               SETREX(rex,cur_eval->u.eval.prev_rex);
+               st->u.eval.prev_rex = rex_sv;           /* inner */
+               SETREX(rex_sv,cur_eval->u.eval.prev_rex);
+               rex = (struct regexp *)SvANY(rex_sv);
                rexi = RXi_GET(rex);
                cur_curlyx = cur_eval->u.eval.prev_curlyx;
-               ReREFCNT_inc(rex);
+               ReREFCNT_inc(rex_sv);
                st->u.eval.cp = regcppush(0);   /* Save *all* the positions. */
+
+               /* rex was changed so update the pointer in PL_reglastparen and PL_reglastcloseparen */
+               PL_reglastparen = &rex->lastparen;
+               PL_reglastcloseparen = &rex->lastcloseparen;
+
                REGCP_SET(st->u.eval.lastcp);
                PL_reginput = locinput;
 
@@ -4875,6 +5184,8 @@ NULL
          do_ifmatch:
            ST.me = scan;
            ST.logical = logical;
+           logical = 0; /* XXX: reset state of logical once it has been saved into ST */
+           
            /* execute body of (?...A) */
            PUSH_YES_STATE_GOTO(IFMATCH_A, NEXTOPER(NEXTOPER(scan)));
            /* NOTREACHED */
@@ -4914,7 +5225,7 @@ NULL
        case PRUNE:
            PL_reginput = locinput;
            if (!scan->flags)
-               sv_yes_mark = sv_commit = (SV*)rexi->data->data[ ARG( scan ) ];
+               sv_yes_mark = sv_commit = MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
            PUSH_STATE_GOTO(COMMIT_next,next);
            /* NOTREACHED */
        case COMMIT_next_fail:
@@ -4928,7 +5239,7 @@ NULL
         case MARKPOINT:
             ST.prev_mark = mark_state;
             ST.mark_name = sv_commit = sv_yes_mark 
-                = (SV*)rexi->data->data[ ARG( scan ) ];
+                = MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
             mark_state = st;
             ST.mark_loc = PL_reginput = locinput;
             PUSH_YES_STATE_GOTO(MARKPOINT_next,next);
@@ -4969,7 +5280,7 @@ NULL
                    otherwise do nothing.  Meaning we need to scan 
                  */
                 regmatch_state *cur = mark_state;
-                SV *find = (SV*)rexi->data->data[ ARG( scan ) ];
+                SV *find = MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
                 
                 while (cur) {
                     if ( sv_eq( cur->u.mark.mark_name, 
@@ -5258,6 +5569,8 @@ S_regrepeat(pTHX_ const regexp *prog, const regnode *p, I32 max, int depth)
     PERL_UNUSED_ARG(depth);
 #endif
 
+    PERL_ARGS_ASSERT_REGREPEAT;
+
     scan = PL_reginput;
     if (max == REG_INFTY)
        max = I32_MAX;
@@ -5419,8 +5732,8 @@ S_regrepeat(pTHX_ const regexp *prog, const regnode *p, I32 max, int depth)
        } else {
            while (scan < loceol && !isSPACE(*scan))
                scan++;
-           break;
        }
+       break;
     case NSPACEL:
        PL_reg_flags |= RF_tainted;
        if (do_utf8) {
@@ -5573,12 +5886,14 @@ Perl_regclass_swash(pTHX_ const regexp *prog, register const regnode* node, bool
     RXi_GET_DECL(prog,progi);
     const struct reg_data * const data = prog ? progi->data : NULL;
 
+    PERL_ARGS_ASSERT_REGCLASS_SWASH;
+
     if (data && data->count) {
        const U32 n = ARG(node);
 
        if (data->what[n] == 's') {
-           SV * const rv = (SV*)data->data[n];
-           AV * const av = (AV*)SvRV((SV*)rv);
+           SV * const rv = MUTABLE_SV(data->data[n]);
+           AV * const av = MUTABLE_AV(SvRV(rv));
            SV **const ary = AvARRAY(av);
            SV **a, **b;
        
@@ -5586,8 +5901,8 @@ Perl_regclass_swash(pTHX_ const regexp *prog, register const regnode* node, bool
             * documentation of these array elements. */
 
            si = *ary;
-           a  = SvROK(ary[1]) ? &ary[1] : 0;
-           b  = SvTYPE(ary[2]) == SVt_PVAV ? &ary[2] : 0;
+           a  = SvROK(ary[1]) ? &ary[1] : NULL;
+           b  = SvTYPE(ary[2]) == SVt_PVAV ? &ary[2] : NULL;
 
            if (a)
                sw = *a;
@@ -5629,10 +5944,14 @@ S_reginclass(pTHX_ const regexp *prog, register const regnode *n, register const
     STRLEN len = 0;
     STRLEN plen;
 
+    PERL_ARGS_ASSERT_REGINCLASS;
+
     if (do_utf8 && !UTF8_IS_INVARIANT(c)) {
        c = utf8n_to_uvchr(p, UTF8_MAXBYTES, &len,
-               (UTF8_ALLOW_DEFAULT & UTF8_ALLOW_ANYUV) | UTF8_CHECK_ONLY);
-               /* see [perl #37836] for UTF8_ALLOW_ANYUV */
+               (UTF8_ALLOW_DEFAULT & UTF8_ALLOW_ANYUV)
+               | UTF8_ALLOW_FFFF | UTF8_CHECK_ONLY);
+               /* see [perl #37836] for UTF8_ALLOW_ANYUV; [perl #38293] for
+                * UTF8_ALLOW_FFFF */
        if (len == (STRLEN)-1) 
            Perl_croak(aTHX_ "Malformed UTF-8 character (fatal)");
     }
@@ -5652,7 +5971,14 @@ S_reginclass(pTHX_ const regexp *prog, register const regnode *n, register const
            SV * const sw = regclass_swash(prog, n, TRUE, 0, (SV**)&av);
        
            if (sw) {
-               if (swash_fetch(sw, p, do_utf8))
+               U8 * utf8_p;
+               if (do_utf8) {
+                   utf8_p = (U8 *) p;
+               } else {
+                   STRLEN len = 1;
+                   utf8_p = bytes_to_utf8(p, &len);
+               }
+               if (swash_fetch(sw, utf8_p, 1))
                    match = TRUE;
                else if (flags & ANYOF_FOLD) {
                    if (!match && lenp && av) {
@@ -5661,8 +5987,7 @@ S_reginclass(pTHX_ const regexp *prog, register const regnode *n, register const
                            SV* const sv = *av_fetch(av, i, FALSE);
                            STRLEN len;
                            const char * const s = SvPV_const(sv, len);
-                       
-                           if (len <= plen && memEQ(s, (char*)p, len)) {
+                           if (len <= plen && memEQ(s, (char*)utf8_p, len)) {
                                *lenp = len;
                                match = TRUE;
                                break;
@@ -5671,13 +5996,16 @@ S_reginclass(pTHX_ const regexp *prog, register const regnode *n, register const
                    }
                    if (!match) {
                        U8 tmpbuf[UTF8_MAXBYTES_CASE+1];
-                       STRLEN tmplen;
 
-                       to_utf8_fold(p, tmpbuf, &tmplen);
-                       if (swash_fetch(sw, tmpbuf, do_utf8))
+                       STRLEN tmplen;
+                       to_utf8_fold(utf8_p, tmpbuf, &tmplen);
+                       if (swash_fetch(sw, tmpbuf, 1))
                            match = TRUE;
                    }
                }
+
+               /* If we allocated a string above, free it */
+               if (! do_utf8) Safefree(utf8_p);
            }
        }
        if (match && lenp && *lenp == 0)
@@ -5746,6 +6074,9 @@ STATIC U8 *
 S_reghop3(U8 *s, I32 off, const U8* lim)
 {
     dVAR;
+
+    PERL_ARGS_ASSERT_REGHOP3;
+
     if (off >= 0) {
        while (off-- && s < lim) {
            /* XXX could check well-formedness here */
@@ -5774,6 +6105,9 @@ STATIC U8 *
 S_reghop4(U8 *s, I32 off, const U8* llim, const U8* rlim)
 {
     dVAR;
+
+    PERL_ARGS_ASSERT_REGHOP4;
+
     if (off >= 0) {
         while (off-- && s < rlim) {
             /* XXX could check well-formedness here */
@@ -5798,6 +6132,9 @@ STATIC U8 *
 S_reghopmaybe3(U8* s, I32 off, const U8* lim)
 {
     dVAR;
+
+    PERL_ARGS_ASSERT_REGHOPMAYBE3;
+
     if (off >= 0) {
        while (off-- && s < lim) {
            /* XXX could check well-formedness here */
@@ -5833,7 +6170,7 @@ restore_pos(pTHX_ void *arg)
 #ifdef PERL_OLD_COPY_ON_WRITE
            rex->saved_copy = PL_nrs;
 #endif
-           RX_MATCH_COPIED_on(rex);
+           RXp_MATCH_COPIED_on(rex);
        }
        PL_reg_magic->mg_len = PL_reg_oldpos;
        PL_reg_eval_set = 0;
@@ -5845,6 +6182,9 @@ STATIC void
 S_to_utf8_substr(pTHX_ register regexp *prog)
 {
     int i = 1;
+
+    PERL_ARGS_ASSERT_TO_UTF8_SUBSTR;
+
     do {
        if (prog->substrs->data[i].substr
            && !prog->substrs->data[i].utf8_substr) {
@@ -5874,6 +6214,9 @@ S_to_byte_substr(pTHX_ register regexp *prog)
 {
     dVAR;
     int i = 1;
+
+    PERL_ARGS_ASSERT_TO_BYTE_SUBSTR;
+
     do {
        if (prog->substrs->data[i].utf8_substr
            && !prog->substrs->data[i].substr) {