This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
document regcomp.c/regexec.c's dual life under ext/re/
[perl5.git] / regexec.c
index 51b55f6..6a7f064 100644 (file)
--- a/regexec.c
+++ b/regexec.c
@@ -5,6 +5,17 @@
  * "One Ring to rule them all, One Ring to find them..."
  */
 
+/* This file contains functions for executing a regular expression.  See
+ * also regcomp.c which funnily enough, contains functions for compiling
+ * a regular expression.
+ *
+ * This file is also copied at build time to ext/re/re_exec.c, where
+ * it's built with -DPERL_EXT_RE_BUILD -DPERL_EXT_RE_DEBUG -DPERL_EXT.
+ * This causes the main functions to be compiled under new names and with
+ * debugging support added, which makes "use re 'debug'" work.
+ */
+
 /* NOTE: this is derived from Henry Spencer's regexp code, and should not
  * confused with the original package (see point 3 below).  Thanks, Henry!
  */
@@ -67,7 +78,8 @@
  *
  ****    Alterations to Henry's code are...
  ****
- ****    Copyright (c) 1991-2001, Larry Wall
+ ****    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
+ ****    2000, 2001, 2002, 2003, 2004, 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.
@@ -86,8 +98,9 @@
 #define RF_warned      2               /* warned about big count? */
 #define RF_evaled      4               /* Did an EVAL with setting? */
 #define RF_utf8                8               /* String contains multibyte chars? */
+#define RF_false       16              /* odd number of nested negatives */
 
-#define UTF (PL_reg_flags & RF_utf8)
+#define UTF ((PL_reg_flags & RF_utf8) != 0)
 
 #define RS_init                1               /* eval environment created */
 #define RS_set         2               /* replsv value is set */
 #define        STATIC  static
 #endif
 
+#define REGINCLASS(p,c)  (ANYOF_FLAGS(p) ? reginclass(p,c,0,0) : ANYOF_BITMAP_TEST(p,*(c)))
+
 /*
  * Forwards.
  */
 
-#define CHR_SVLEN(sv) (UTF ? sv_len_utf8(sv) : SvCUR(sv))
+#define CHR_SVLEN(sv) (do_utf8 ? sv_len_utf8(sv) : SvCUR(sv))
 #define CHR_DIST(a,b) (PL_reg_match_utf8 ? utf8_distance(a,b) : a - b)
 
 #define reghop_c(pos,off) ((char*)reghop((U8*)pos, off))
 #define HOPMAYBEc(pos,off) ((char*)HOPMAYBE(pos,off))
 
 #define HOPBACK(pos, off) (            \
-    (UTF && PL_reg_match_utf8)         \
+    (PL_reg_match_utf8)                        \
        ? reghopmaybe((U8*)pos, -off)   \
     : (pos - off >= PL_bostr)          \
        ? (U8*)(pos - off)              \
 #define HOP3c(pos,off,lim) ((char*)HOP3(pos,off,lim))
 #define HOPMAYBE3c(pos,off,lim) ((char*)HOPMAYBE3(pos,off,lim))
 
-#define LOAD_UTF8_CHARCLASS(a,b) STMT_START { if (!CAT2(PL_utf8_,a)) (void)CAT2(is_utf8_, a)((U8*)b); } STMT_END
+#define LOAD_UTF8_CHARCLASS(a,b) STMT_START { if (!CAT2(PL_utf8_,a)) { ENTER; save_re_context(); (void)CAT2(is_utf8_, a)((U8*)b); LEAVE; } } STMT_END
 
 /* for use after a quantifier and before an EXACT-like node -- japhy */
 #define JUMPABLE(rn) ( \
     PL_regkind[(U8)OP(rn)] == EXACT || PL_regkind[(U8)OP(rn)] == REF \
 )
 
+/*
+  Search for mandatory following text node; for lookahead, the text must
+  follow but for lookbehind (rn->flags != 0) we skip to the next step.
+*/
 #define FIND_NEXT_IMPT(rn) STMT_START { \
     while (JUMPABLE(rn)) \
-       if (OP(rn) == SUSPEND || OP(rn) == IFMATCH || \
-           PL_regkind[(U8)OP(rn)] == CURLY) \
+       if (OP(rn) == SUSPEND || PL_regkind[(U8)OP(rn)] == CURLY) \
            rn = NEXTOPER(NEXTOPER(rn)); \
        else if (OP(rn) == PLUS) \
            rn = NEXTOPER(rn); \
+       else if (OP(rn) == IFMATCH) \
+           rn = (rn->flags == 0) ? NEXTOPER(NEXTOPER(rn)) : rn + ARG(rn); \
        else rn += NEXT_OFF(rn); \
 } STMT_END 
 
@@ -164,7 +184,7 @@ S_regcppush(pTHX_ I32 parenfloor)
        Perl_croak(aTHX_ "panic: paren_elems_to_push < 0");
 
 #define REGCP_OTHER_ELEMS 6
-    SSCHECK(paren_elems_to_push + REGCP_OTHER_ELEMS);
+    SSGROW(paren_elems_to_push + REGCP_OTHER_ELEMS);
     for (p = PL_regsize; p > parenfloor; p--) {
 /* REGCP_PARENS_ELEMS are pushed per pairs of parentheses. */
        SSPUSHINT(PL_regendp[p]);
@@ -232,7 +252,7 @@ S_regcppop(pTHX)
        );
     }
     DEBUG_r(
-       if (*PL_reglastparen + 1 <= PL_regnpar) {
+       if ((I32)(*PL_reglastparen + 1) <= PL_regnpar) {
            PerlIO_printf(Perl_debug_log,
                          "     restoring \\%"IVdf"..\\%"IVdf" to undef\n",
                          (IV)(*PL_reglastparen + 1), (IV)PL_regnpar);
@@ -249,8 +269,8 @@ S_regcppop(pTHX)
      * building DynaLoader will fail:
      * "Error: '*' not in typemap in DynaLoader.xs, line 164"
      * --jhi */
-    for (paren = *PL_reglastparen + 1; paren <= PL_regnpar; paren++) {
-       if (paren > PL_regsize)
+    for (paren = *PL_reglastparen + 1; (I32)paren <= PL_regnpar; paren++) {
+       if ((I32)paren > PL_regsize)
            PL_regstartp[paren] = -1;
        PL_regendp[paren] = -1;
     }
@@ -385,13 +405,16 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
     register SV *check;
     char *strbeg;
     char *t;
+    int do_utf8 = sv ? SvUTF8(sv) : 0; /* if no sv we have to assume bytes */
     I32 ml_anch;
     register char *other_last = Nullch;        /* other substr checked before this */
     char *check_at = Nullch;           /* check substr found at this pos */
+    I32 multiline = prog->reganch & PMf_MULTILINE;
 #ifdef DEBUGGING
     char *i_strpos = strpos;
     SV *dsv = PERL_DEBUG_PAD_ZERO(0);
 #endif
+    RX_MATCH_UTF8_set(prog,do_utf8);
 
     if (prog->reganch & ROPT_UTF8) {
        DEBUG_r(PerlIO_printf(Perl_debug_log,
@@ -401,7 +424,8 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
 
     DEBUG_r({
         char *s   = PL_reg_match_utf8 ?
-                        sv_uni_display(dsv, sv, 60, 0) : strpos;
+                        sv_uni_display(dsv, sv, 60, UNI_DISPLAY_REGEX) :
+                        strpos;
         int   len = PL_reg_match_utf8 ?
                         strlen(s) : strend - strpos;
         if (!PL_colorset)
@@ -422,18 +446,32 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
              );
     });
 
-    if (prog->minlen > CHR_DIST((U8*)strend, (U8*)strpos)) {
+    /* CHR_DIST() would be more correct here but it makes things slow. */
+    if (prog->minlen > strend - strpos) {
        DEBUG_r(PerlIO_printf(Perl_debug_log,
                              "String too short... [re_intuit_start]\n"));
        goto fail;
     }
     strbeg = (sv && SvPOK(sv)) ? strend - SvCUR(sv) : strpos;
     PL_regeol = strend;
-    check = prog->check_substr;
+    if (do_utf8) {
+       if (!prog->check_utf8 && prog->check_substr)
+           to_utf8_substr(prog);
+       check = prog->check_utf8;
+    } else {
+       if (!prog->check_substr && prog->check_utf8)
+           to_byte_substr(prog);
+       check = prog->check_substr;
+    }
+   if (check == &PL_sv_undef) {
+       DEBUG_r(PerlIO_printf(Perl_debug_log,
+               "Non-utf string cannot match utf check string\n"));
+       goto fail;
+    }
     if (prog->reganch & ROPT_ANCH) {   /* Match at beg-of-str or after \n */
        ml_anch = !( (prog->reganch & ROPT_ANCH_SINGLE)
                     || ( (prog->reganch & ROPT_ANCH_BOL)
-                         && !PL_multiline ) ); /* Check after \n? */
+                         && !multiline ) );    /* Check after \n? */
 
        if (!ml_anch) {
          if ( !(prog->reganch & (ROPT_ANCH_GPOS /* Checked by the caller */
@@ -518,24 +556,27 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                            start_shift + (s - strbeg), end_shift, pp, 0);
        else
            goto fail_finish;
+       /* we may be pointing at the wrong string */
+       if (s && RX_MATCH_COPIED(prog))
+           s = strbeg + (s - SvPVX(sv));
        if (data)
            *data->scream_olds = s;
     }
     else if (prog->reganch & ROPT_CANY_SEEN)
        s = fbm_instr((U8*)(s + start_shift),
                      (U8*)(strend - end_shift),
-                     check, PL_multiline ? FBMrf_MULTILINE : 0);
+                     check, multiline ? FBMrf_MULTILINE : 0);
     else
        s = fbm_instr(HOP3(s, start_shift, strend),
                      HOP3(strend, -end_shift, strbeg),
-                     check, PL_multiline ? FBMrf_MULTILINE : 0);
+                     check, multiline ? FBMrf_MULTILINE : 0);
 
     /* Update the count-of-usability, remove useless subpatterns,
        unshift s.  */
 
     DEBUG_r(PerlIO_printf(Perl_debug_log, "%s %s substr `%s%.*s%s'%s%s",
                          (s ? "Found" : "Did not find"),
-                         ((check == prog->anchored_substr) ? "anchored" : "floating"),
+                         (check == (do_utf8 ? prog->anchored_utf8 : prog->anchored_substr) ? "anchored" : "floating"),
                          PL_colors[0],
                          (int)(SvCUR(check) - (SvTAIL(check)!=0)),
                          SvPVX(check),
@@ -558,20 +599,21 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
        Probably it is right to do no SCREAM here...
      */
 
-    if (prog->float_substr && prog->anchored_substr) {
+    if (do_utf8 ? (prog->float_utf8 && prog->anchored_utf8) : (prog->float_substr && prog->anchored_substr)) {
        /* Take into account the "other" substring. */
        /* XXXX May be hopelessly wrong for UTF... */
        if (!other_last)
            other_last = strpos;
-       if (check == prog->float_substr) {
+       if (check == (do_utf8 ? prog->float_utf8 : prog->float_substr)) {
          do_other_anchored:
            {
                char *last = HOP3c(s, -start_shift, strbeg), *last1, *last2;
                char *s1 = s;
+               SV* must;
 
                t = s - prog->check_offset_max;
                if (s - strpos > prog->check_offset_max  /* signed-corrected t > strpos */
-                   && (!(prog->reganch & ROPT_UTF8)
+                   && (!do_utf8
                        || ((t = reghopmaybe3_c(s, -(prog->check_offset_max), strpos))
                            && t > strpos)))
                    /* EMPTY */;
@@ -585,20 +627,27 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                    last1 = last;
  /* XXXX It is not documented what units *_offsets are in.  Assume bytes.  */
                /* On end-of-str: see comment below. */
-               s = fbm_instr((unsigned char*)t,
-                             HOP3(HOP3(last1, prog->anchored_offset, strend)
-                                  + SvCUR(prog->anchored_substr),
-                                  -(SvTAIL(prog->anchored_substr)!=0), strbeg),
-                             prog->anchored_substr,
-                             PL_multiline ? FBMrf_MULTILINE : 0);
+               must = do_utf8 ? prog->anchored_utf8 : prog->anchored_substr;
+               if (must == &PL_sv_undef) {
+                   s = (char*)NULL;
+                   DEBUG_r(must = prog->anchored_utf8);        /* for debug */
+               }
+               else
+                   s = fbm_instr(
+                       (unsigned char*)t,
+                       HOP3(HOP3(last1, prog->anchored_offset, strend)
+                               + SvCUR(must), -(SvTAIL(must)!=0), strbeg),
+                       must,
+                       multiline ? FBMrf_MULTILINE : 0
+                   );
                DEBUG_r(PerlIO_printf(Perl_debug_log,
                        "%s anchored substr `%s%.*s%s'%s",
                        (s ? "Found" : "Contradicts"),
                        PL_colors[0],
-                         (int)(SvCUR(prog->anchored_substr)
-                         - (SvTAIL(prog->anchored_substr)!=0)),
-                         SvPVX(prog->anchored_substr),
-                         PL_colors[1], (SvTAIL(prog->anchored_substr) ? "$" : "")));
+                         (int)(SvCUR(must)
+                         - (SvTAIL(must)!=0)),
+                         SvPVX(must),
+                         PL_colors[1], (SvTAIL(must) ? "$" : "")));
                if (!s) {
                    if (last1 >= last2) {
                        DEBUG_r(PerlIO_printf(Perl_debug_log,
@@ -625,60 +674,66 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
            }
        }
        else {          /* Take into account the floating substring. */
-               char *last, *last1;
-               char *s1 = s;
-
-               t = HOP3c(s, -start_shift, strbeg);
-               last1 = last =
-                   HOP3c(strend, -prog->minlen + prog->float_min_offset, strbeg);
-               if (CHR_DIST((U8*)last, (U8*)t) > prog->float_max_offset)
-                   last = HOP3c(t, prog->float_max_offset, strend);
-               s = HOP3c(t, prog->float_min_offset, strend);
-               if (s < other_last)
-                   s = other_last;
+           char *last, *last1;
+           char *s1 = s;
+           SV* must;
+
+           t = HOP3c(s, -start_shift, strbeg);
+           last1 = last =
+               HOP3c(strend, -prog->minlen + prog->float_min_offset, strbeg);
+           if (CHR_DIST((U8*)last, (U8*)t) > prog->float_max_offset)
+               last = HOP3c(t, prog->float_max_offset, strend);
+           s = HOP3c(t, prog->float_min_offset, strend);
+           if (s < other_last)
+               s = other_last;
  /* XXXX It is not documented what units *_offsets are in.  Assume bytes.  */
-               /* fbm_instr() takes into account exact value of end-of-str
-                  if the check is SvTAIL(ed).  Since false positives are OK,
-                  and end-of-str is not later than strend we are OK. */
+           must = do_utf8 ? prog->float_utf8 : prog->float_substr;
+           /* fbm_instr() takes into account exact value of end-of-str
+              if the check is SvTAIL(ed).  Since false positives are OK,
+              and end-of-str is not later than strend we are OK. */
+           if (must == &PL_sv_undef) {
+               s = (char*)NULL;
+               DEBUG_r(must = prog->float_utf8);       /* for debug message */
+           }
+           else
                s = fbm_instr((unsigned char*)s,
-                             (unsigned char*)last + SvCUR(prog->float_substr)
-                                 - (SvTAIL(prog->float_substr)!=0),
-                             prog->float_substr, PL_multiline ? FBMrf_MULTILINE : 0);
-               DEBUG_r(PerlIO_printf(Perl_debug_log, "%s floating substr `%s%.*s%s'%s",
-                       (s ? "Found" : "Contradicts"),
-                       PL_colors[0],
-                         (int)(SvCUR(prog->float_substr)
-                         - (SvTAIL(prog->float_substr)!=0)),
-                         SvPVX(prog->float_substr),
-                         PL_colors[1], (SvTAIL(prog->float_substr) ? "$" : "")));
-               if (!s) {
-                   if (last1 == last) {
-                       DEBUG_r(PerlIO_printf(Perl_debug_log,
-                                               ", giving up...\n"));
-                       goto fail_finish;
-                   }
+                             (unsigned char*)last + SvCUR(must)
+                                 - (SvTAIL(must)!=0),
+                             must, multiline ? FBMrf_MULTILINE : 0);
+           DEBUG_r(PerlIO_printf(Perl_debug_log, "%s floating substr `%s%.*s%s'%s",
+                   (s ? "Found" : "Contradicts"),
+                   PL_colors[0],
+                     (int)(SvCUR(must) - (SvTAIL(must)!=0)),
+                     SvPVX(must),
+                     PL_colors[1], (SvTAIL(must) ? "$" : "")));
+           if (!s) {
+               if (last1 == last) {
                    DEBUG_r(PerlIO_printf(Perl_debug_log,
-                       ", trying anchored starting at offset %ld...\n",
-                       (long)(s1 + 1 - i_strpos)));
-                   other_last = last;
-                   s = HOP3c(t, 1, strend);
-                   goto restart;
-               }
-               else {
-                   DEBUG_r(PerlIO_printf(Perl_debug_log, " at offset %ld...\n",
-                         (long)(s - i_strpos)));
-                   other_last = s; /* Fix this later. --Hugo */
-                   s = s1;
-                   if (t == strpos)
-                       goto try_at_start;
-                   goto try_at_offset;
+                                           ", giving up...\n"));
+                   goto fail_finish;
                }
+               DEBUG_r(PerlIO_printf(Perl_debug_log,
+                   ", trying anchored starting at offset %ld...\n",
+                   (long)(s1 + 1 - i_strpos)));
+               other_last = last;
+               s = HOP3c(t, 1, strend);
+               goto restart;
+           }
+           else {
+               DEBUG_r(PerlIO_printf(Perl_debug_log, " at offset %ld...\n",
+                     (long)(s - i_strpos)));
+               other_last = s; /* Fix this later. --Hugo */
+               s = s1;
+               if (t == strpos)
+                   goto try_at_start;
+               goto try_at_offset;
+           }
        }
     }
 
     t = s - prog->check_offset_max;
     if (s - strpos > prog->check_offset_max  /* signed-corrected t > strpos */
-        && (!(prog->reganch & ROPT_UTF8)
+        && (!do_utf8
            || ((t = reghopmaybe3_c(s, -prog->check_offset_max, strpos))
                 && t > strpos))) {
        /* Fixed substring is found far enough so that the match
@@ -695,7 +750,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
            while (t < strend - prog->minlen) {
                if (*t == '\n') {
                    if (t < check_at - prog->check_offset_min) {
-                       if (prog->anchored_substr) {
+                       if (do_utf8 ? prog->anchored_utf8 : prog->anchored_substr) {
                            /* Since we moved from the found position,
                               we definitely contradict the found anchored
                               substr.  Due to the above check we do not
@@ -735,7 +790,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
        }
        s = t;
       set_useful:
-       ++BmUSEFUL(prog->check_substr); /* hooray/5 */
+       ++BmUSEFUL(do_utf8 ? prog->check_utf8 : prog->check_substr);    /* hooray/5 */
     }
     else {
        /* The found string does not prohibit matching at strpos,
@@ -759,15 +814,23 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
        );
       success_at_start:
        if (!(prog->reganch & ROPT_NAUGHTY)     /* XXXX If strpos moved? */
-           && prog->check_substr               /* Could be deleted already */
-           && --BmUSEFUL(prog->check_substr) < 0
-           && prog->check_substr == prog->float_substr)
+           && (do_utf8 ? (
+               prog->check_utf8                /* Could be deleted already */
+               && --BmUSEFUL(prog->check_utf8) < 0
+               && (prog->check_utf8 == prog->float_utf8)
+           ) : (
+               prog->check_substr              /* Could be deleted already */
+               && --BmUSEFUL(prog->check_substr) < 0
+               && (prog->check_substr == prog->float_substr)
+           )))
        {
            /* If flags & SOMETHING - do not do it many times on the same match */
            DEBUG_r(PerlIO_printf(Perl_debug_log, "... Disabling check substring...\n"));
-           SvREFCNT_dec(prog->check_substr);
-           prog->check_substr = Nullsv;        /* disable */
-           prog->float_substr = Nullsv;        /* clear */
+           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);
+           prog->check_substr = prog->check_utf8 = Nullsv;     /* disable */
+           prog->float_substr = prog->float_utf8 = Nullsv;     /* clear */
            check = Nullsv;                     /* abort */
            s = strpos;
            /* XXXX This is a remnant of the old implementation.  It
@@ -794,19 +857,16 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
        int cl_l = (PL_regkind[(U8)OP(prog->regstclass)] == EXACT
                    ? CHR_DIST(str+STR_LEN(prog->regstclass), str)
                    : 1);
-       char *endpos = (prog->anchored_substr || ml_anch)
+       char *endpos = (prog->anchored_substr || prog->anchored_utf8 || ml_anch)
                ? HOP3c(s, (prog->minlen ? cl_l : 0), strend)
-               : (prog->float_substr
+               : (prog->float_substr || prog->float_utf8
                   ? HOP3c(HOP3c(check_at, -start_shift, strbeg),
                           cl_l, strend)
                   : strend);
        char *startpos = strbeg;
 
        t = s;
-       if (prog->reganch & ROPT_UTF8) {        
-           PL_regdata = prog->data;
-           PL_bostr = startpos;
-       }
+       cache_re(prog);
        s = find_byclass(prog, prog->regstclass, s, endpos, startpos, 1);
        if (!s) {
 #ifdef DEBUGGING
@@ -822,8 +882,8 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
            if ((prog->reganch & ROPT_ANCH) && !ml_anch)
                goto fail;
            /* Contradict one of substrings */
-           if (prog->anchored_substr) {
-               if (prog->anchored_substr == check) {
+           if (prog->anchored_substr || prog->anchored_utf8) {
+               if ((do_utf8 ? prog->anchored_utf8 : prog->anchored_substr) == check) {
                    DEBUG_r( what = "anchored" );
                  hop_and_restart:
                    s = HOP3c(t, 1, strend);
@@ -863,7 +923,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                          PL_colors[0],PL_colors[1], (long)(t - i_strpos)) );
                goto try_at_offset;
            }
-           if (!prog->float_substr)    /* Could have been deleted */
+           if (!(do_utf8 ? prog->float_utf8 : prog->float_substr))     /* Could have been deleted */
                goto fail;
            /* Check is floating subtring. */
          retry_floating_check:
@@ -890,8 +950,8 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
     return s;
 
   fail_finish:                         /* Substring not found */
-    if (prog->check_substr)            /* could be removed already */
-       BmUSEFUL(prog->check_substr) += 5; /* hooray */
+    if (prog->check_substr || prog->check_utf8)                /* could be removed already */
+       BmUSEFUL(do_utf8 ? prog->check_utf8 : prog->check_substr) += 5; /* hooray */
   fail:
     DEBUG_r(PerlIO_printf(Perl_debug_log, "%sMatch rejected by optimizer%s\n",
                          PL_colors[4],PL_colors[5]));
@@ -905,6 +965,8 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        I32 doevery = (prog->reganch & ROPT_SKIP) == 0;
        char *m;
        STRLEN ln;
+       STRLEN lnc;
+       register STRLEN uskip;
        unsigned int c1;
        unsigned int c2;
        char *e;
@@ -914,16 +976,40 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        /* We know what class it must start with. */
        switch (OP(c)) {
        case ANYOF:
-           while (s < strend) {
-               if (reginclass(c, (U8*)s, do_utf8)) {
-                   if (tmp && (norun || regtry(prog, s)))
-                       goto got_it;
-                   else
-                       tmp = doevery;
-               }
-               else
-                   tmp = 1;
-               s += do_utf8 ? UTF8SKIP(s) : 1;
+           if (do_utf8) {
+                while (s + (uskip = UTF8SKIP(s)) <= strend) {
+                     if ((ANYOF_FLAGS(c) & ANYOF_UNICODE) ||
+                         !UTF8_IS_INVARIANT((U8)s[0]) ?
+                         reginclass(c, (U8*)s, 0, do_utf8) :
+                         REGINCLASS(c, (U8*)s)) {
+                          if (tmp && (norun || regtry(prog, s)))
+                               goto got_it;
+                          else
+                               tmp = doevery;
+                     }
+                     else 
+                          tmp = 1;
+                     s += uskip;
+                }
+           }
+           else {
+                while (s < strend) {
+                     STRLEN skip = 1;
+
+                     if (REGINCLASS(c, (U8*)s) ||
+                         (ANYOF_FOLD_SHARP_S(c, s, strend) &&
+                          /* The assignment of 2 is intentional:
+                           * for the folded sharp s, the skip is 2. */
+                          (skip = SHARP_S_SKIP))) {
+                          if (tmp && (norun || regtry(prog, s)))
+                               goto got_it;
+                          else
+                               tmp = doevery;
+                     }
+                     else 
+                          tmp = 1;
+                     s += skip;
+                }
            }
            break;
        case CANY:
@@ -936,18 +1022,27 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
            }
            break;
        case EXACTF:
-           m = STRING(c);
-           ln = STR_LEN(c);
+           m   = STRING(c);
+           ln  = STR_LEN(c);   /* length to match in octets/bytes */
+           lnc = (I32) ln;     /* length to match in characters */
            if (UTF) {
                STRLEN ulen1, ulen2;
+               U8 *sm = (U8 *) m;
                U8 tmpbuf1[UTF8_MAXLEN_UCLC+1];
                U8 tmpbuf2[UTF8_MAXLEN_UCLC+1];
 
                to_utf8_lower((U8*)m, tmpbuf1, &ulen1);
                to_utf8_upper((U8*)m, tmpbuf2, &ulen2);
 
-               c1 = utf8_to_uvuni(tmpbuf1, 0);
-               c2 = utf8_to_uvuni(tmpbuf2, 0);
+               c1 = utf8n_to_uvchr(tmpbuf1, UTF8_MAXLEN_UCLC, 
+                                   0, ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY);
+               c2 = utf8n_to_uvchr(tmpbuf2, UTF8_MAXLEN_UCLC,
+                                   0, ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY);
+               lnc = 0;
+               while (sm < ((U8 *) m + ln)) {
+                   lnc++;
+                   sm += UTF8SKIP(sm);
+               }
            }
            else {
                c1 = *(U8*)m;
@@ -955,12 +1050,13 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
            }
            goto do_exactf;
        case EXACTFL:
-           m = STRING(c);
-           ln = STR_LEN(c);
+           m   = STRING(c);
+           ln  = STR_LEN(c);
+           lnc = (I32) ln;
            c1 = *(U8*)m;
            c2 = PL_fold_locale[c1];
          do_exactf:
-           e = do_utf8 ? s + ln - 1 : strend - ln;
+           e = HOP3c(strend, -((I32)lnc), s);
 
            if (norun && e < s)
                e = s;                  /* Due to minlen logic of intuit() */
@@ -971,25 +1067,28 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
             * text of the node.  The c1 and c2 are the first
             * characters (though in Unicode it gets a bit
             * more complicated because there are more cases
-            * than just upper and lower: one is really supposed
-            * to use the so-called folding case for case-insensitive
-            * matching (called "loose matching" in Unicode).  */
+            * than just upper and lower: one needs to use
+            * the so-called folding case for case-insensitive
+            * matching (called "loose matching" in Unicode).
+            * ibcmp_utf8() will do just that. */
 
            if (do_utf8) {
                UV c, f;
                U8 tmpbuf [UTF8_MAXLEN+1];
                U8 foldbuf[UTF8_MAXLEN_FOLD+1];
                STRLEN len, foldlen;
-               char* se;
                
                if (c1 == c2) {
+                   /* Upper and lower of 1st char are equal -
+                    * probably not a "letter". */
                    while (s <= e) {
-                       c = utf8_to_uvchr((U8*)s, &len);
+                       c = utf8n_to_uvchr((U8*)s, UTF8_MAXLEN, &len,
+                                          ckWARN(WARN_UTF8) ?
+                                          0 : UTF8_ALLOW_ANY);
                        if ( c == c1
                             && (ln == len ||
-                                ((se = e + 1) &&
-                                 !ibcmp_utf8(s, &se, 0,  do_utf8,
-                                             m, 0  , ln, UTF)))
+                                ibcmp_utf8(s, (char **)0, 0,  do_utf8,
+                                           m, (char **)0, ln, (bool)UTF))
                             && (norun || regtry(prog, s)) )
                            goto got_it;
                        else {
@@ -998,10 +1097,10 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                             if ( f != c
                                  && (f == c1 || f == c2)
                                  && (ln == foldlen ||
-                                     !ibcmp_utf8((char *)foldbuf,
-                                                 0, foldlen, do_utf8,
+                                     !ibcmp_utf8((char *) foldbuf,
+                                                 (char **)0, foldlen, do_utf8,
                                                  m,
-                                                 0, ln,      UTF))
+                                                 (char **)0, ln, (bool)UTF))
                                  && (norun || regtry(prog, s)) )
                                  goto got_it;
                        }
@@ -1010,24 +1109,25 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                }
                else {
                    while (s <= e) {
-                       c = utf8_to_uvchr((U8*)s, &len);
+                     c = utf8n_to_uvchr((U8*)s, UTF8_MAXLEN, &len,
+                                          ckWARN(WARN_UTF8) ?
+                                          0 : UTF8_ALLOW_ANY);
 
                        /* Handle some of the three Greek sigmas cases.
-                         * Note that not all the possible combinations
-                         * are handled here: some of them are handled
-                         * handled by the standard folding rules, and
-                         * some of them (the character class or ANYOF
-                         * cases) are handled during compiletime in
-                         * regexec.c:S_regclass(). */
+                        * Note that not all the possible combinations
+                        * are handled here: some of them are handled
+                        * by the standard folding rules, and some of
+                        * them (the character class or ANYOF cases)
+                        * are handled during compiletime in
+                        * regexec.c:S_regclass(). */
                        if (c == (UV)UNICODE_GREEK_CAPITAL_LETTER_SIGMA ||
                            c == (UV)UNICODE_GREEK_SMALL_LETTER_FINAL_SIGMA)
                            c = (UV)UNICODE_GREEK_SMALL_LETTER_SIGMA;
 
                        if ( (c == c1 || c == c2)
                             && (ln == len ||
-                                ((se = e + 1) &&
-                                 !ibcmp_utf8(s, &se, 0,  do_utf8,
-                                             m, 0,   ln, UTF)))
+                                ibcmp_utf8(s, (char **)0, 0,  do_utf8,
+                                           m, (char **)0, ln, (bool)UTF))
                             && (norun || regtry(prog, s)) )
                            goto got_it;
                        else {
@@ -1036,10 +1136,10 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                             if ( f != c
                                  && (f == c1 || f == c2)
                                  && (ln == foldlen ||
-                                     !ibcmp_utf8((char *)foldbuf,
-                                                 0, foldlen, do_utf8,
+                                     !ibcmp_utf8((char *) foldbuf,
+                                                 (char **)0, foldlen, do_utf8,
                                                  m,
-                                                 0, ln,      UTF))
+                                                 (char **)0, ln, (bool)UTF))
                                  && (norun || regtry(prog, s)) )
                                  goto got_it;
                        }
@@ -1078,15 +1178,14 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                if (s == PL_bostr)
                    tmp = '\n';
                else {
-                   U8 *r = reghop3((U8*)s, -1, (U8*)startpos);
+                   U8 *r = reghop3((U8*)s, -1, (U8*)PL_bostr);
                
-                   if (s > (char*)r)
-                       tmp = (I32)utf8n_to_uvchr(r, s - (char*)r, 0, 0);
+                   tmp = utf8n_to_uvchr(r, UTF8SKIP(r), 0, 0);
                }
                tmp = ((OP(c) == BOUND ?
                        isALNUM_uni(tmp) : isALNUM_LC_uvchr(UNI_TO_NATIVE(tmp))) != 0);
                LOAD_UTF8_CHARCLASS(alnum,"a");
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (tmp == !(OP(c) == BOUND ?
                                 swash_fetch(PL_utf8_alnum, (U8*)s, do_utf8) :
                                 isALNUM_LC_utf8((U8*)s)))
@@ -1095,7 +1194,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                        if ((norun || regtry(prog, s)))
                            goto got_it;
                    }
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1122,22 +1221,21 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                if (s == PL_bostr)
                    tmp = '\n';
                else {
-                   U8 *r = reghop3((U8*)s, -1, (U8*)startpos);
+                   U8 *r = reghop3((U8*)s, -1, (U8*)PL_bostr);
                
-                   if (s > (char*)r)
-                       tmp = (I32)utf8n_to_uvchr(r, s - (char*)r, 0, 0);
+                   tmp = utf8n_to_uvchr(r, UTF8SKIP(r), 0, 0);
                }
                tmp = ((OP(c) == NBOUND ?
                        isALNUM_uni(tmp) : isALNUM_LC_uvchr(UNI_TO_NATIVE(tmp))) != 0);
                LOAD_UTF8_CHARCLASS(alnum,"a");
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (tmp == !(OP(c) == NBOUND ?
                                 swash_fetch(PL_utf8_alnum, (U8*)s, do_utf8) :
                                 isALNUM_LC_utf8((U8*)s)))
                        tmp = !tmp;
                    else if ((norun || regtry(prog, s)))
                        goto got_it;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1159,7 +1257,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case ALNUM:
            if (do_utf8) {
                LOAD_UTF8_CHARCLASS(alnum,"a");
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (swash_fetch(PL_utf8_alnum, (U8*)s, do_utf8)) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1168,7 +1266,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1188,7 +1286,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case ALNUML:
            PL_reg_flags |= RF_tainted;
            if (do_utf8) {
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (isALNUM_LC_utf8((U8*)s)) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1197,7 +1295,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1217,7 +1315,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case NALNUM:
            if (do_utf8) {
                LOAD_UTF8_CHARCLASS(alnum,"a");
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (!swash_fetch(PL_utf8_alnum, (U8*)s, do_utf8)) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1226,7 +1324,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1246,7 +1344,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case NALNUML:
            PL_reg_flags |= RF_tainted;
            if (do_utf8) {
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (!isALNUM_LC_utf8((U8*)s)) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1255,7 +1353,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1275,7 +1373,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case SPACE:
            if (do_utf8) {
                LOAD_UTF8_CHARCLASS(space," ");
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (*s == ' ' || swash_fetch(PL_utf8_space,(U8*)s, do_utf8)) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1284,7 +1382,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1304,7 +1402,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case SPACEL:
            PL_reg_flags |= RF_tainted;
            if (do_utf8) {
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (*s == ' ' || isSPACE_LC_utf8((U8*)s)) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1313,7 +1411,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1333,7 +1431,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case NSPACE:
            if (do_utf8) {
                LOAD_UTF8_CHARCLASS(space," ");
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (!(*s == ' ' || swash_fetch(PL_utf8_space,(U8*)s, do_utf8))) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1342,7 +1440,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1362,7 +1460,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case NSPACEL:
            PL_reg_flags |= RF_tainted;
            if (do_utf8) {
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (!(*s == ' ' || isSPACE_LC_utf8((U8*)s))) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1371,7 +1469,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1391,7 +1489,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case DIGIT:
            if (do_utf8) {
                LOAD_UTF8_CHARCLASS(digit,"0");
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (swash_fetch(PL_utf8_digit,(U8*)s, do_utf8)) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1400,7 +1498,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1420,7 +1518,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case DIGITL:
            PL_reg_flags |= RF_tainted;
            if (do_utf8) {
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (isDIGIT_LC_utf8((U8*)s)) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1429,7 +1527,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1449,7 +1547,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case NDIGIT:
            if (do_utf8) {
                LOAD_UTF8_CHARCLASS(digit,"0");
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (!swash_fetch(PL_utf8_digit,(U8*)s, do_utf8)) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1458,7 +1556,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1478,7 +1576,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
        case NDIGITL:
            PL_reg_flags |= RF_tainted;
            if (do_utf8) {
-               while (s < strend) {
+               while (s + (uskip = UTF8SKIP(s)) <= strend) {
                    if (!isDIGIT_LC_utf8((U8*)s)) {
                        if (tmp && (norun || regtry(prog, s)))
                            goto got_it;
@@ -1487,7 +1585,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1537,9 +1635,12 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
     char *scream_olds;
     SV* oreplsv = GvSV(PL_replgv);
     bool do_utf8 = DO_UTF8(sv);
+    I32 multiline = prog->reganch & PMf_MULTILINE;
 #ifdef DEBUGGING
-    SV *dsv = PERL_DEBUG_PAD_ZERO(0);
+    SV *dsv0 = PERL_DEBUG_PAD_ZERO(0);
+    SV *dsv1 = PERL_DEBUG_PAD_ZERO(1);
 #endif
+    RX_MATCH_UTF8_set(prog,do_utf8);
 
     PL_regcc = 0;
 
@@ -1610,8 +1711,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
            PL_reg_ganch = strbeg;
     }
 
-    if (do_utf8 == (UTF!=0) &&
-       !(flags & REXEC_CHECKED) && prog->check_substr != Nullsv) {
+    if (!(flags & REXEC_CHECKED) && (prog->check_substr != Nullsv || prog->check_utf8 != Nullsv)) {
        re_scream_pos_data d;
 
        d.scream_olds = &scream_olds;
@@ -1624,20 +1724,26 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
     }
 
     DEBUG_r({
-        char *s   = do_utf8 ? sv_uni_display(dsv, sv, 60, 0) : startpos;
-        int   len = do_utf8 ? strlen(s) : strend - startpos;
+        char *s0   = UTF ?
+          pv_uni_display(dsv0, (U8*)prog->precomp, prog->prelen, 60,
+                         UNI_DISPLAY_REGEX) :
+          prog->precomp;
+        int   len0 = UTF ? SvCUR(dsv0) : prog->prelen;
+        char *s1   = do_utf8 ? sv_uni_display(dsv1, sv, 60,
+                                              UNI_DISPLAY_REGEX) : startpos;
+        int   len1 = do_utf8 ? SvCUR(dsv1) : strend - startpos;
         if (!PL_colorset)
             reginitcolors();
         PerlIO_printf(Perl_debug_log,
-                      "%sMatching REx%s `%s%.60s%s%s' against `%s%.*s%s%s'\n",
+                      "%sMatching REx%s `%s%*.*s%s%s' against `%s%.*s%s%s'\n",
                       PL_colors[4],PL_colors[5],PL_colors[0],
-                      prog->precomp,
+                      len0, len0, s0,
                       PL_colors[1],
-                      (strlen(prog->precomp) > 60 ? "..." : ""),
+                      len0 > 60 ? "..." : "",
                       PL_colors[0],
-                      (int)(len > 60 ? 60 : len),
-                      s, PL_colors[1],
-                      (len > 60 ? "..." : "")
+                      (int)(len1 > 60 ? 60 : len1),
+                      s1, PL_colors[1],
+                      (len1 > 60 ? "..." : "")
              );
     });
 
@@ -1646,7 +1752,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
     if (prog->reganch & (ROPT_ANCH & ~ROPT_ANCH_GPOS)) {
        if (s == startpos && regtry(prog, startpos))
            goto got_it;
-       else if (PL_multiline || (prog->reganch & ROPT_IMPLICIT)
+       else if (multiline || (prog->reganch & ROPT_IMPLICIT)
                 || (prog->reganch & ROPT_ANCH_MBOL)) /* XXXX SBOL? */
        {
            char *end;
@@ -1655,7 +1761,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
                dontbother = minlen - 1;
            end = HOP3c(strend, -dontbother, strbeg) - 1;
            /* for multiline we only have to try after newlines */
-           if (prog->check_substr) {
+           if (prog->check_substr || prog->check_utf8) {
                if (s == startpos)
                    goto after_try;
                while (1) {
@@ -1691,13 +1797,16 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
     }
 
     /* Messy cases:  unanchored match. */
-    if (prog->anchored_substr && prog->reganch & ROPT_SKIP) {
+    if ((prog->anchored_substr || prog->anchored_utf8) && prog->reganch & ROPT_SKIP) {
        /* we have /x+whatever/ */
        /* it must be a one character string (XXXX Except UTF?) */
-       char ch = SvPVX(prog->anchored_substr)[0];
+       char ch;
 #ifdef DEBUGGING
        int did_match = 0;
 #endif
+       if (!(do_utf8 ? prog->anchored_utf8 : prog->anchored_substr))
+           do_utf8 ? to_utf8_substr(prog) : to_byte_substr(prog);
+       ch = SvPVX(do_utf8 ? prog->anchored_utf8 : prog->anchored_substr)[0];
 
        if (do_utf8) {
            while (s < strend) {
@@ -1729,23 +1838,37 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
                );
     }
     /*SUPPRESS 560*/
-    else if (do_utf8 == (UTF!=0) &&
-            (prog->anchored_substr != Nullsv
-             || (prog->float_substr != Nullsv
-                 && prog->float_max_offset < strend - s))) {
-       SV *must = prog->anchored_substr
-           ? prog->anchored_substr : prog->float_substr;
-       I32 back_max =
-           prog->anchored_substr ? prog->anchored_offset : prog->float_max_offset;
-       I32 back_min =
-           prog->anchored_substr ? prog->anchored_offset : prog->float_min_offset;
-       char *last = HOP3c(strend,      /* Cannot start after this */
-                         -(I32)(CHR_SVLEN(must)
-                                - (SvTAIL(must) != 0) + back_min), strbeg);
+    else if (prog->anchored_substr != Nullsv
+             || prog->anchored_utf8 != Nullsv
+             || ((prog->float_substr != Nullsv || prog->float_utf8 != Nullsv)
+                 && prog->float_max_offset < strend - s)) {
+       SV *must;
+       I32 back_max;
+       I32 back_min;
+       char *last;
        char *last1;            /* Last position checked before */
 #ifdef DEBUGGING
        int did_match = 0;
 #endif
+       if (prog->anchored_substr || prog->anchored_utf8) {
+           if (!(do_utf8 ? prog->anchored_utf8 : prog->anchored_substr))
+               do_utf8 ? to_utf8_substr(prog) : to_byte_substr(prog);
+           must = do_utf8 ? prog->anchored_utf8 : prog->anchored_substr;
+           back_max = back_min = prog->anchored_offset;
+       } else {
+           if (!(do_utf8 ? prog->float_utf8 : prog->float_substr))
+               do_utf8 ? to_utf8_substr(prog) : to_byte_substr(prog);
+           must = do_utf8 ? prog->float_utf8 : prog->float_substr;
+           back_max = prog->float_max_offset;
+           back_min = prog->float_min_offset;
+       }
+       if (must == &PL_sv_undef)
+           /* could not downgrade utf8 check substring, so must fail */
+           goto phooey;
+
+       last = HOP3c(strend,    /* Cannot start after this */
+                         -(I32)(CHR_SVLEN(must)
+                                - (SvTAIL(must) != 0) + back_min), strbeg);
 
        if (s > PL_bostr)
            last1 = HOPc(s, -1);
@@ -1763,7 +1886,10 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
                                    end_shift, &scream_pos, 0))
                 : (s = fbm_instr((unsigned char*)HOP3(s, back_min, strend),
                                  (unsigned char*)strend, must,
-                                 PL_multiline ? FBMrf_MULTILINE : 0))) ) {
+                                 multiline ? FBMrf_MULTILINE : 0))) ) {
+           /* we may be pointing at the wrong string */
+           if ((flags & REXEC_SCREAM) && RX_MATCH_COPIED(prog))
+               s = strbeg + (s - SvPVX(sv));
            DEBUG_r( did_match = 1 );
            if (HOPc(s, -back_max) > last1) {
                last1 = HOPc(s, -back_min);
@@ -1793,7 +1919,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
        DEBUG_r(if (!did_match)
                     PerlIO_printf(Perl_debug_log, 
                                   "Did not find %s substr `%s%.*s%s'%s...\n",
-                             ((must == prog->anchored_substr)
+                             ((must == prog->anchored_substr || must == prog->anchored_utf8)
                               ? "anchored" : "floating"),
                              PL_colors[0],
                              (int)(SvCUR(must) - (SvTAIL(must)!=0)),
@@ -1803,13 +1929,32 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
        goto phooey;
     }
     else if ((c = prog->regstclass)) {
-       if (minlen && PL_regkind[(U8)OP(prog->regstclass)] != EXACT)
+       if (minlen) {
+           I32 op = (U8)OP(prog->regstclass);
            /* don't bother with what can't match */
-           strend = HOPc(strend, -(minlen - 1));
+           if (PL_regkind[op] != EXACT && op != CANY)
+               strend = HOPc(strend, -(minlen - 1));
+       }
        DEBUG_r({
            SV *prop = sv_newmortal();
+           char *s0;
+           char *s1;
+           int len0;
+           int len1;
+
            regprop(prop, c);
-           PerlIO_printf(Perl_debug_log, "Matching stclass `%s' against `%s'\n", SvPVX(prop), UTF ? sv_uni_display(dsv, sv, 60, 0) : s);
+           s0 = UTF ?
+             pv_uni_display(dsv0, (U8*)SvPVX(prop), SvCUR(prop), 60,
+                            UNI_DISPLAY_REGEX) :
+             SvPVX(prop);
+           len0 = UTF ? SvCUR(dsv0) : SvCUR(prop);
+           s1 = UTF ?
+             sv_uni_display(dsv1, sv, 60, UNI_DISPLAY_REGEX) : s;
+           len1 = UTF ? SvCUR(dsv1) : strend - s;
+           PerlIO_printf(Perl_debug_log,
+                         "Matching stclass `%*.*s' against `%*.*s'\n",
+                         len0, len0, s0,
+                         len1, len1, s1);
        });
        if (find_byclass(prog, c, s, strend, startpos, 0))
            goto got_it;
@@ -1817,23 +1962,32 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
     }
     else {
        dontbother = 0;
-       if (prog->float_substr != Nullsv) {     /* Trim the end. */
+       if (prog->float_substr != Nullsv || prog->float_utf8 != Nullsv) {
+           /* Trim the end. */
            char *last;
+           SV* float_real;
+
+           if (!(do_utf8 ? prog->float_utf8 : prog->float_substr))
+               do_utf8 ? to_utf8_substr(prog) : to_byte_substr(prog);
+           float_real = do_utf8 ? prog->float_utf8 : prog->float_substr;
 
            if (flags & REXEC_SCREAM) {
-               last = screaminstr(sv, prog->float_substr, s - strbeg,
+               last = screaminstr(sv, float_real, s - strbeg,
                                   end_shift, &scream_pos, 1); /* last one */
                if (!last)
                    last = scream_olds; /* Only one occurrence. */
+               /* we may be pointing at the wrong string */
+               else if (RX_MATCH_COPIED(prog))
+                   s = strbeg + (s - SvPVX(sv));
            }
            else {
                STRLEN len;
-               char *little = SvPV(prog->float_substr, len);
+               char *little = SvPV(float_real, len);
 
-               if (SvTAIL(prog->float_substr)) {
+               if (SvTAIL(float_real)) {
                    if (memEQ(strend - len + 1, little, len - 1))
                        last = strend - len + 1;
-                   else if (!PL_multiline)
+                   else if (!multiline)
                        last = memEQ(strend - len, little, len)
                            ? strend - len : Nullch;
                    else
@@ -1892,17 +2046,28 @@ got_it:
 
     /* make sure $`, $&, $', and $digit will work later */
     if ( !(flags & REXEC_NOT_FIRST) ) {
-       if (RX_MATCH_COPIED(prog)) {
-           Safefree(prog->subbeg);
-           RX_MATCH_COPIED_off(prog);
-       }
+       RX_MATCH_COPY_FREE(prog);
        if (flags & REXEC_COPY_STR) {
            I32 i = PL_regeol - startpos + (stringarg - strbeg);
-
-           s = savepvn(strbeg, i);
-           prog->subbeg = s;
+#ifdef PERL_COPY_ON_WRITE
+           if ((SvIsCOW(sv)
+                || (SvFLAGS(sv) & CAN_COW_MASK) == CAN_COW_FLAGS)) {
+               if (DEBUG_C_TEST) {
+                   PerlIO_printf(Perl_debug_log,
+                                 "Copy on write: regexp capture, type %d\n",
+                                 (int) SvTYPE(sv));
+               }
+               prog->saved_copy = sv_setsv_cow(prog->saved_copy, sv);
+               prog->subbeg = SvPVX(prog->saved_copy);
+               assert (SvPOKp(prog->saved_copy));
+           } else
+#endif
+           {
+               RX_MATCH_COPIED_on(prog);
+               s = savepvn(strbeg, i);
+               prog->subbeg = s;
+           }
            prog->sublen = i;
-           RX_MATCH_COPIED_on(prog);
        }
        else {
            prog->subbeg = strbeg;
@@ -1953,8 +2118,7 @@ S_regtry(pTHX_ regexp *prog, char *startpos)
        if (PL_reg_sv) {
            /* Make $_ available to executed code. */
            if (PL_reg_sv != DEFSV) {
-               /* SAVE_DEFSV does *not* suffice here for USE_5005THREADS */
-               SAVESPTR(DEFSV);
+               SAVE_DEFSV;
                DEFSV = PL_reg_sv;
            }
        
@@ -1992,6 +2156,9 @@ S_regtry(pTHX_ regexp *prog, char *startpos)
                $` inside (?{}) could fail... */
            PL_reg_oldsaved = prog->subbeg;
            PL_reg_oldsavedlen = prog->sublen;
+#ifdef PERL_COPY_ON_WRITE
+           PL_nrs = prog->saved_copy;
+#endif
            RX_MATCH_COPIED_off(prog);
        }
        else
@@ -2006,6 +2173,7 @@ S_regtry(pTHX_ regexp *prog, char *startpos)
     PL_reglastparen = &prog->lastparen;
     PL_reglastcloseparen = &prog->lastcloseparen;
     prog->lastparen = 0;
+    prog->lastcloseparen = 0;
     PL_regsize = 0;
     DEBUG_r(PL_reg_starttry = startpos);
     if (PL_reg_start_tmpl <= prog->nparens) {
@@ -2016,12 +2184,6 @@ S_regtry(pTHX_ regexp *prog, char *startpos)
             New(22,PL_reg_start_tmp, PL_reg_start_tmpl, char*);
     }
 
-#ifdef DEBUGGING
-    sv_setpvn(PERL_DEBUG_PAD(0), "", 0);
-    sv_setpvn(PERL_DEBUG_PAD(1), "", 0);
-    sv_setpvn(PERL_DEBUG_PAD(2), "", 0);
-#endif
-
     /* XXXX What this code is doing here?!!!  There should be no need
        to do this again and again, PL_reglastparen should take care of
        this!  --ilya*/
@@ -2040,7 +2202,7 @@ S_regtry(pTHX_ regexp *prog, char *startpos)
     sp = prog->startp;
     ep = prog->endp;
     if (prog->nparens) {
-       for (i = prog->nparens; i > *PL_reglastparen; i--) {
+       for (i = prog->nparens; i > (I32)*PL_reglastparen; i--) {
            *++sp = -1;
            *++ep = -1;
        }
@@ -2087,6 +2249,7 @@ typedef union re_unwind_t {
 
 #define sayYES goto yes
 #define sayNO goto no
+#define sayNO_ANYOF goto no_anyof
 #define sayYES_FINAL goto yes_final
 #define sayYES_LOUD  goto yes_loud
 #define sayNO_FINAL  goto no_final
@@ -2173,19 +2336,19 @@ S_regmatch(pTHX_ regnode *prog)
            regprop(prop, scan);
            {
              char *s0 =
-               do_utf8 ?
+               do_utf8 && OP(scan) != CANY ?
                pv_uni_display(dsv0, (U8*)(locinput - pref_len),
-                              pref0_len, 60, 0) :
+                              pref0_len, 60, UNI_DISPLAY_REGEX) :
                locinput - pref_len;
              int len0 = do_utf8 ? strlen(s0) : pref0_len;
-             char *s1 = do_utf8 ?
+             char *s1 = do_utf8 && OP(scan) != CANY ?
                pv_uni_display(dsv1, (U8*)(locinput - pref_len + pref0_len),
-                              pref_len - pref0_len, 60, 0) :
+                              pref_len - pref0_len, 60, UNI_DISPLAY_REGEX) :
                locinput - pref_len + pref0_len;
              int len1 = do_utf8 ? strlen(s1) : pref_len - pref0_len;
-             char *s2 = do_utf8 ?
+             char *s2 = do_utf8 && OP(scan) != CANY ?
                pv_uni_display(dsv2, (U8*)locinput,
-                              PL_regeol - locinput, 60, 0) :
+                              PL_regeol - locinput, 60, UNI_DISPLAY_REGEX) :
                locinput;
              int len2 = do_utf8 ? strlen(s2) : l;
              PerlIO_printf(Perl_debug_log,
@@ -2214,8 +2377,7 @@ S_regmatch(pTHX_ regnode *prog)
 
        switch (OP(scan)) {
        case BOL:
-           if (locinput == PL_bostr || (PL_multiline &&
-               (nextchr || locinput < PL_regeol) && locinput[-1] == '\n') )
+           if (locinput == PL_bostr)
            {
                /* regtill = regbol; */
                break;
@@ -2237,12 +2399,8 @@ S_regmatch(pTHX_ regnode *prog)
                break;
            sayNO;
        case EOL:
-           if (PL_multiline)
-               goto meol;
-           else
                goto seol;
        case MEOL:
-         meol:
            if ((nextchr || locinput < PL_regeol) && nextchr != '\n')
                sayNO;
            break;
@@ -2289,7 +2447,7 @@ S_regmatch(pTHX_ regnode *prog)
        case EXACT:
            s = STRING(scan);
            ln = STR_LEN(scan);
-           if (do_utf8 != (UTF!=0)) {
+           if (do_utf8 != UTF) {
                /* The target and the pattern have differing utf8ness. */
                char *l = locinput;
                char *e = s + ln;
@@ -2301,7 +2459,9 @@ S_regmatch(pTHX_ regnode *prog)
                        if (l >= PL_regeol)
                             sayNO;
                        if (NATIVE_TO_UNI(*(U8*)s) !=
-                           utf8_to_uvchr((U8*)l, &ulen))
+                           utf8n_to_uvuni((U8*)l, UTF8_MAXLEN, &ulen,
+                                          ckWARN(WARN_UTF8) ?
+                                          0 : UTF8_ALLOW_ANY))
                             sayNO;
                        l += ulen;
                        s ++;
@@ -2313,7 +2473,9 @@ S_regmatch(pTHX_ regnode *prog)
                        if (l >= PL_regeol)
                            sayNO;
                        if (NATIVE_TO_UNI(*((U8*)l)) !=
-                           utf8_to_uvchr((U8*)s, &ulen))
+                           utf8n_to_uvuni((U8*)s, UTF8_MAXLEN, &ulen,
+                                          ckWARN(WARN_UTF8) ?
+                                          0 : UTF8_ALLOW_ANY))
                            sayNO;
                        s += ulen;
                        l ++;
@@ -2346,9 +2508,21 @@ S_regmatch(pTHX_ regnode *prog)
                char *l = locinput;
                char *e = PL_regeol;
 
-               if (ibcmp_utf8(s, 0,  ln, do_utf8,
-                              l, &e, 0,  UTF))
-                    sayNO;
+               if (ibcmp_utf8(s, 0,  ln, (bool)UTF,
+                              l, &e, 0,  do_utf8)) {
+                    /* One more case for the sharp s:
+                     * pack("U0U*", 0xDF) =~ /ss/i,
+                     * the 0xC3 0x9F are the UTF-8
+                     * byte sequence for the U+00DF. */
+                    if (!(do_utf8 &&
+                          toLOWER(s[0]) == 's' &&
+                          ln >= 2 &&
+                          toLOWER(s[1]) == 's' &&
+                          (U8)l[0] == 0xC3 &&
+                          e - l >= 2 &&
+                          (U8)l[1] == 0x9F))
+                         sayNO;
+               }
                locinput = e;
                nextchr = UCHARAT(locinput);
                break;
@@ -2372,22 +2546,36 @@ S_regmatch(pTHX_ regnode *prog)
            break;
        case ANYOF:
            if (do_utf8) {
-               if (!reginclass(scan, (U8*)locinput, do_utf8))
-                   sayNO;
+               STRLEN inclasslen = PL_regeol - locinput;
+
+               if (!reginclass(scan, (U8*)locinput, &inclasslen, do_utf8))
+                   sayNO_ANYOF;
                if (locinput >= PL_regeol)
                    sayNO;
-               locinput += PL_utf8skip[nextchr];
+               locinput += inclasslen ? inclasslen : UTF8SKIP(locinput);
                nextchr = UCHARAT(locinput);
+               break;
            }
            else {
                if (nextchr < 0)
                    nextchr = UCHARAT(locinput);
-               if (!reginclass(scan, (U8*)locinput, do_utf8))
-                   sayNO;
+               if (!REGINCLASS(scan, (U8*)locinput))
+                   sayNO_ANYOF;
                if (!nextchr && locinput >= PL_regeol)
                    sayNO;
                nextchr = UCHARAT(++locinput);
+               break;
            }
+       no_anyof:
+           /* 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;
@@ -2446,9 +2634,9 @@ S_regmatch(pTHX_ regnode *prog)
                if (locinput == PL_bostr)
                    ln = '\n';
                else {
-                   U8 *r = reghop((U8*)locinput, -1);
+                   U8 *r = reghop3((U8*)locinput, -1, (U8*)PL_bostr);
                
-                   ln = utf8n_to_uvchr(r, s - (char*)r, 0, 0);
+                   ln = utf8n_to_uvchr(r, UTF8SKIP(r), 0, 0);
                }
                if (OP(scan) == BOUND || OP(scan) == NBOUND) {
                    ln = isALNUM_uni(ln);
@@ -2602,7 +2790,7 @@ S_regmatch(pTHX_ regnode *prog)
            n = ARG(scan);  /* which paren pair */
            ln = PL_regstartp[n];
            PL_reg_leftiter = PL_reg_maxiter;           /* Void cache */
-           if (*PL_reglastparen < n || ln == -1)
+           if ((I32)*PL_reglastparen < n || ln == -1)
                sayNO;                  /* Do not match unless seen CLOSEn. */
            if (ln == PL_regendp[n])
                break;
@@ -2665,13 +2853,14 @@ S_regmatch(pTHX_ regnode *prog)
            dSP;
            OP_4tree *oop = PL_op;
            COP *ocurcop = PL_curcop;
-           SV **ocurpad = PL_curpad;
+           PAD *old_comppad;
            SV *ret;
+           struct regexp *oreg = PL_reg_re;
        
            n = ARG(scan);
            PL_op = (OP_4tree*)PL_regdata->data[n];
            DEBUG_r( PerlIO_printf(Perl_debug_log, "  re_eval 0x%"UVxf"\n", PTR2UV(PL_op)) );
-           PL_curpad = AvARRAY((AV*)PL_regdata->data[n + 2]);
+           PAD_SAVE_LOCAL(old_comppad, (PAD*)PL_regdata->data[n + 2]);
            PL_regendp[0] = PL_reg_magic->mg_len = locinput - PL_bostr;
 
            {
@@ -2679,7 +2868,7 @@ S_regmatch(pTHX_ regnode *prog)
                CALLRUNOPS(aTHX);                       /* Scalar context. */
                SPAGAIN;
                if (SP == before)
-                   ret = Nullsv;   /* protect against empty (?{}) blocks. */
+                   ret = &PL_sv_undef;   /* protect against empty (?{}) blocks. */
                else {
                    ret = POPs;
                    PUTBACK;
@@ -2687,7 +2876,7 @@ S_regmatch(pTHX_ regnode *prog)
            }
 
            PL_op = oop;
-           PL_curpad = ocurpad;
+           PAD_RESTORE_LOCAL(old_comppad);
            PL_curcop = ocurcop;
            if (logical) {
                if (logical == 2) {     /* Postponed subexpression. */
@@ -2695,13 +2884,18 @@ S_regmatch(pTHX_ regnode *prog)
                    MAGIC *mg = Null(MAGIC*);
                    re_cc_state state;
                    CHECKPOINT cp, lastcp;
-
-                   if(SvROK(ret) || SvRMAGICAL(ret)) {
-                       SV *sv = SvROK(ret) ? SvRV(ret) : ret;
-
-                       if(SvMAGICAL(sv))
-                           mg = mg_find(sv, PERL_MAGIC_qr);
+                    int toggleutf;
+                   register SV *sv;
+
+                   if(SvROK(ret) && SvSMAGICAL(sv = SvRV(ret)))
+                       mg = mg_find(sv, PERL_MAGIC_qr);
+                   else if (SvSMAGICAL(ret)) {
+                       if (SvGMAGICAL(ret))
+                           sv_unmagic(ret, PERL_MAGIC_qr);
+                       else
+                           mg = mg_find(ret, PERL_MAGIC_qr);
                    }
+
                    if (mg) {
                        re = (regexp *)mg->mg_obj;
                        (void)ReREFCNT_inc(re);
@@ -2715,9 +2909,11 @@ S_regmatch(pTHX_ regnode *prog)
                        I32 onpar = PL_regnpar;
 
                        Zero(&pm, 1, PMOP);
+                        if (DO_UTF8(ret)) pm.op_pmdynflags |= PMdf_DYN_UTF8;
                        re = CALLREGCOMP(aTHX_ t, t + len, &pm);
                        if (!(SvFLAGS(ret)
-                             & (SVs_TEMP | SVs_PADTMP | SVf_READONLY)))
+                             & (SVs_TEMP | SVs_PADTMP | SVf_READONLY
+                               | SVs_GMG)))
                            sv_magic(ret,(SV*)ReREFCNT_inc(re),
                                        PERL_MAGIC_qr,0,0);
                        PL_regprecomp = oprecomp;
@@ -2747,6 +2943,9 @@ S_regmatch(pTHX_ regnode *prog)
                    *PL_reglastcloseparen = 0;
                    PL_reg_call_cc = &state;
                    PL_reginput = locinput;
+                   toggleutf = ((PL_reg_flags & RF_utf8) != 0) ^
+                               ((re->reganch & ROPT_UTF8) != 0);
+                   if (toggleutf) PL_reg_flags ^= RF_utf8;
 
                    /* XXXX This is too dramatic a measure... */
                    PL_reg_maxiter = 0;
@@ -2761,6 +2960,7 @@ S_regmatch(pTHX_ regnode *prog)
                        PL_regcc = state.cc;
                        PL_reg_re = state.re;
                        cache_re(PL_reg_re);
+                       if (toggleutf) PL_reg_flags ^= RF_utf8;
 
                        /* XXXX This is too dramatic a measure... */
                        PL_reg_maxiter = 0;
@@ -2777,6 +2977,7 @@ S_regmatch(pTHX_ regnode *prog)
                    PL_regcc = state.cc;
                    PL_reg_re = state.re;
                    cache_re(PL_reg_re);
+                   if (toggleutf) PL_reg_flags ^= RF_utf8;
 
                    /* XXXX This is too dramatic a measure... */
                    PL_reg_maxiter = 0;
@@ -2787,8 +2988,10 @@ S_regmatch(pTHX_ regnode *prog)
                sw = SvTRUE(ret);
                logical = 0;
            }
-           else
+           else {
                sv_setsv(save_scalar(PL_replgv), ret);
+               cache_re(oreg);
+           }
            break;
        }
        case OPEN:
@@ -2801,13 +3004,13 @@ S_regmatch(pTHX_ regnode *prog)
            n = ARG(scan);  /* which paren pair */
            PL_regstartp[n] = PL_reg_start_tmp[n] - PL_bostr;
            PL_regendp[n] = locinput - PL_bostr;
-           if (n > *PL_reglastparen)
+           if (n > (I32)*PL_reglastparen)
                *PL_reglastparen = n;
            *PL_reglastcloseparen = n;
            break;
        case GROUPP:
            n = ARG(scan);  /* which paren pair */
-           sw = (*PL_reglastparen >= n && PL_regendp[n] != -1);
+           sw = ((I32)*PL_reglastparen >= n && PL_regendp[n] != -1);
            break;
        case IFTHEN:
            PL_reg_leftiter = PL_reg_maxiter;           /* Void cache */
@@ -2909,7 +3112,7 @@ S_regmatch(pTHX_ regnode *prog)
                PL_regcc = &cc;
                /* XXXX Probably it is better to teach regpush to support
                   parenfloor > PL_regsize... */
-               if (parenfloor > *PL_reglastparen)
+               if (parenfloor > (I32)*PL_reglastparen)
                    parenfloor = *PL_reglastparen; /* Pessimization... */
                cc.parenfloor = parenfloor;
                cc.cur = -1;
@@ -2945,10 +3148,10 @@ S_regmatch(pTHX_ regnode *prog)
 
                DEBUG_r(
                    PerlIO_printf(Perl_debug_log,
-                                 "%*s  %ld out of %ld..%ld  cc=%lx\n",
+                                 "%*s  %ld out of %ld..%ld  cc=%"UVxf"\n",
                                  REPORT_CODE_OFF+PL_regindent*2, "",
                                  (long)n, (long)cc->min,
-                                 (long)cc->max, (long)cc)
+                                 (long)cc->max, PTR2UV(cc))
                    );
 
                /* If degenerate scan matches "", assume scan done. */
@@ -2993,7 +3196,7 @@ S_regmatch(pTHX_ regnode *prog)
                if (PL_reg_leftiter-- == 0) {
                    I32 size = (PL_reg_maxiter + 7)/8;
                    if (PL_reg_poscache) {
-                       if (PL_reg_poscache_size < size) {
+                       if ((I32)PL_reg_poscache_size < size) {
                            Renew(PL_reg_poscache, size, char);
                            PL_reg_poscache_size = size;
                        }
@@ -3021,7 +3224,10 @@ S_regmatch(pTHX_ regnode *prog)
                                      "%*s  already tried at this position...\n",
                                      REPORT_CODE_OFF+PL_regindent*2, "")
                        );
-                       sayNO_SILENT;
+                       if (PL_reg_flags & RF_false)
+                           sayYES;
+                       else
+                           sayNO_SILENT;
                    }
                    PL_reg_poscache[o] |= (1<<b);
                }
@@ -3049,7 +3255,7 @@ S_regmatch(pTHX_ regnode *prog)
                        if (ckWARN(WARN_REGEXP) && n >= REG_INFTY
                            && !(PL_reg_flags & RF_warned)) {
                            PL_reg_flags |= RF_warned;
-                           Perl_warner(aTHX_ WARN_REGEXP, "%s limit (%d) exceeded",
+                           Perl_warner(aTHX_ packWARN(WARN_REGEXP), "%s limit (%d) exceeded",
                                 "Complex regular subexpression recursion",
                                 REG_INFTY - 1);
                        }
@@ -3101,7 +3307,7 @@ S_regmatch(pTHX_ regnode *prog)
                if (ckWARN(WARN_REGEXP) && n >= REG_INFTY
                        && !(PL_reg_flags & RF_warned)) {
                    PL_reg_flags |= RF_warned;
-                   Perl_warner(aTHX_ WARN_REGEXP, "%s limit (%d) exceeded",
+                   Perl_warner(aTHX_ packWARN(WARN_REGEXP), "%s limit (%d) exceeded",
                         "Complex regular subexpression recursion",
                         REG_INFTY - 1);
                }
@@ -3170,7 +3376,7 @@ S_regmatch(pTHX_ regnode *prog)
            CHECKPOINT lastcp;
        
            /* We suppose that the next guy does not need
-              backtracking: in particular, it is of constant length,
+              backtracking: in particular, it is of constant non-zero length,
               and has no parenths to influence future backrefs. */
            ln = ARG1(scan);  /* min to match */
            n  = ARG2(scan);  /* max to match */
@@ -3178,7 +3384,7 @@ S_regmatch(pTHX_ regnode *prog)
            if (paren) {
                if (paren > PL_regsize)
                    PL_regsize = paren;
-               if (paren > *PL_reglastparen)
+               if (paren > (I32)*PL_reglastparen)
                    *PL_reglastparen = paren;
            }
            scan = NEXTOPER(scan) + NODE_STEP_REGNODE;
@@ -3189,15 +3395,6 @@ S_regmatch(pTHX_ regnode *prog)
                minmod = 0;
                if (ln && regrepeat_hard(scan, ln, &l) < ln)
                    sayNO;
-               /* if we matched something zero-length we don't need to
-                  backtrack - capturing parens are already defined, so
-                  the caveat in the maximal case doesn't apply
-
-                  XXXX if ln == 0, we can redo this check first time
-                  through the following loop
-               */
-               if (ln && l == 0)
-                   n = ln;     /* don't backtrack */
                locinput = PL_reginput;
                if (HAS_TEXT(next) || JUMPABLE(next)) {
                    regnode *text_node = next;
@@ -3207,19 +3404,8 @@ S_regmatch(pTHX_ regnode *prog)
                    if (! HAS_TEXT(text_node)) c1 = c2 = -1000;
                    else {
                        if (PL_regkind[(U8)OP(text_node)] == REF) {
-                           I32 n, ln;
-                           n = ARG(text_node);  /* which paren pair */
-                           ln = PL_regstartp[n];
-                           /* assume yes if we haven't seen CLOSEn */
-                           if (
-                               *PL_reglastparen < n ||
-                               ln == -1 ||
-                               ln == PL_regendp[n]
-                           ) {
-                               c1 = c2 = -1000;
-                               goto assume_ok_MM;
-                           }
-                           c1 = *(PL_bostr + ln);
+                           c1 = c2 = -1000;
+                           goto assume_ok_MM;
                        }
                        else { c1 = (U8)*STRING(text_node); }
                        if (OP(text_node) == EXACTF || OP(text_node) == REFF)
@@ -3234,8 +3420,7 @@ S_regmatch(pTHX_ regnode *prog)
                    c1 = c2 = -1000;
            assume_ok_MM:
                REGCP_SET(lastcp);
-               /* This may be improved if l == 0.  */
-               while (n >= ln || (n == REG_INFTY && ln > 0 && l)) { /* ln overflow ? */
+               while (n >= ln || (n == REG_INFTY && ln > 0)) { /* ln overflow ? */
                    /* If it could work, try it. */
                    if (c1 == -1000 ||
                        UCHARAT(PL_reginput) == c1 ||
@@ -3266,13 +3451,6 @@ S_regmatch(pTHX_ regnode *prog)
            }
            else {
                n = regrepeat_hard(scan, n, &l);
-               /* if we matched something zero-length we don't need to
-                  backtrack, unless the minimum count is zero and we
-                  are capturing the result - in that case the capture
-                  being defined or not may affect later execution
-               */
-               if (n != 0 && l == 0 && !(paren && ln == 0))
-                   ln = n;     /* don't backtrack */
                locinput = PL_reginput;
                DEBUG_r(
                    PerlIO_printf(Perl_debug_log,
@@ -3289,19 +3467,8 @@ S_regmatch(pTHX_ regnode *prog)
                        if (! HAS_TEXT(text_node)) c1 = c2 = -1000;
                        else {
                            if (PL_regkind[(U8)OP(text_node)] == REF) {
-                               I32 n, ln;
-                               n = ARG(text_node);  /* which paren pair */
-                               ln = PL_regstartp[n];
-                               /* assume yes if we haven't seen CLOSEn */
-                               if (
-                                   *PL_reglastparen < n ||
-                                   ln == -1 ||
-                                   ln == PL_regendp[n]
-                               ) {
-                                   c1 = c2 = -1000;
-                                   goto assume_ok_REG;
-                               }
-                               c1 = *(PL_bostr + ln);
+                               c1 = c2 = -1000;
+                               goto assume_ok_REG;
                            }
                            else { c1 = (U8)*STRING(text_node); }
 
@@ -3354,7 +3521,7 @@ S_regmatch(pTHX_ regnode *prog)
            paren = scan->flags;        /* Which paren to set */
            if (paren > PL_regsize)
                PL_regsize = paren;
-           if (paren > *PL_reglastparen)
+           if (paren > (I32)*PL_reglastparen)
                *PL_reglastparen = paren;
            ln = ARG1(scan);  /* min to match */
            n  = ARG2(scan);  /* max to match */
@@ -3398,19 +3565,8 @@ S_regmatch(pTHX_ regnode *prog)
                if (! HAS_TEXT(text_node)) c1 = c2 = -1000;
                else {
                    if (PL_regkind[(U8)OP(text_node)] == REF) {
-                       I32 n, ln;
-                       n = ARG(text_node);  /* which paren pair */
-                       ln = PL_regstartp[n];
-                       /* assume yes if we haven't seen CLOSEn */
-                       if (
-                           *PL_reglastparen < n ||
-                           ln == -1 ||
-                           ln == PL_regendp[n]
-                       ) {
-                           c1 = c2 = -1000;
-                           goto assume_ok_easy;
-                       }
-                       s = (U8*)PL_bostr + ln;
+                       c1 = c2 = -1000;
+                       goto assume_ok_easy;
                    }
                    else { s = (U8*)STRING(text_node); }
 
@@ -3430,11 +3586,17 @@ S_regmatch(pTHX_ regnode *prog)
                             to_utf8_lower((U8*)s, tmpbuf1, &ulen1);
                             to_utf8_upper((U8*)s, tmpbuf2, &ulen2);
 
-                            c1 = utf8_to_uvuni(tmpbuf1, 0);
-                            c2 = utf8_to_uvuni(tmpbuf2, 0);
+                            c1 = utf8n_to_uvuni(tmpbuf1, UTF8_MAXLEN, 0,
+                                                ckWARN(WARN_UTF8) ?
+                                                0 : UTF8_ALLOW_ANY);
+                            c2 = utf8n_to_uvuni(tmpbuf2, UTF8_MAXLEN, 0,
+                                                ckWARN(WARN_UTF8) ?
+                                                0 : UTF8_ALLOW_ANY);
                        }
                        else {
-                           c2 = c1 = utf8_to_uvchr(s, NULL);
+                           c2 = c1 = utf8n_to_uvchr(s, UTF8_MAXLEN, 0,
+                                                    ckWARN(WARN_UTF8) ?
+                                                    0 : UTF8_ALLOW_ANY);
                        }
                    }
                }
@@ -3453,6 +3615,7 @@ S_regmatch(pTHX_ regnode *prog)
                if (c1 != -1000) {
                    char *e; /* Should not check after this */
                    char *old = locinput;
+                   int count = 0;
 
                    if  (n == REG_INFTY) {
                        e = PL_regeol - 1;
@@ -3472,7 +3635,6 @@ S_regmatch(pTHX_ regnode *prog)
                            e = PL_regeol - 1;
                    }
                    while (1) {
-                       int count;
                        /* Find place 'next' could work */
                        if (!do_utf8) {
                            if (c1 == c2) {
@@ -3490,18 +3652,28 @@ S_regmatch(pTHX_ regnode *prog)
                        else {
                            STRLEN len;
                            if (c1 == c2) {
-                               for (count = 0;
-                                    locinput <= e &&
-                                        utf8_to_uvchr((U8*)locinput, &len) != c1;
-                                    count++)
+                               /* count initialised to
+                                * utf8_distance(old, locinput) */
+                               while (locinput <= e &&
+                                      utf8n_to_uvchr((U8*)locinput,
+                                                     UTF8_MAXLEN, &len,
+                                                     ckWARN(WARN_UTF8) ?
+                                                     0 : UTF8_ALLOW_ANY) != (UV)c1) {
                                    locinput += len;
-                               
+                                   count++;
+                               }
                            } else {
-                               for (count = 0; locinput <= e; count++) {
-                                   UV c = utf8_to_uvchr((U8*)locinput, &len);
-                                   if (c == c1 || c == c2)
+                               /* count initialised to
+                                * utf8_distance(old, locinput) */
+                               while (locinput <= e) {
+                                   UV c = utf8n_to_uvchr((U8*)locinput,
+                                                         UTF8_MAXLEN, &len,
+                                                         ckWARN(WARN_UTF8) ?
+                                                         0 : UTF8_ALLOW_ANY);
+                                   if (c == (UV)c1 || c == (UV)c2)
                                        break;
-                                   locinput += len;                    
+                                   locinput += len;
+                                   count++;
                                }
                            }
                        }
@@ -3523,6 +3695,7 @@ S_regmatch(pTHX_ regnode *prog)
                            locinput += UTF8SKIP(locinput);
                        else
                            locinput++;
+                       count = 1;
                    }
                }
                else
@@ -3530,20 +3703,23 @@ S_regmatch(pTHX_ regnode *prog)
                    UV c;
                    if (c1 != -1000) {
                        if (do_utf8)
-                           c = utf8_to_uvchr((U8*)PL_reginput, NULL);
+                           c = utf8n_to_uvchr((U8*)PL_reginput,
+                                              UTF8_MAXLEN, 0,
+                                              ckWARN(WARN_UTF8) ?
+                                              0 : UTF8_ALLOW_ANY);
                        else
                            c = UCHARAT(PL_reginput);
                        /* If it could work, try it. */
-                       if (c == c1 || c == c2)
+                       if (c == (UV)c1 || c == (UV)c2)
                        {
-                           TRYPAREN(paren, n, PL_reginput);
+                           TRYPAREN(paren, ln, PL_reginput);
                            REGCP_UNWIND(lastcp);
                        }
                    }
                    /* If it could work, try it. */
                    else if (c1 == -1000)
                    {
-                       TRYPAREN(paren, n, PL_reginput);
+                       TRYPAREN(paren, ln, PL_reginput);
                        REGCP_UNWIND(lastcp);
                    }
                    /* Couldn't or didn't -- move forward. */
@@ -3561,7 +3737,9 @@ S_regmatch(pTHX_ regnode *prog)
                n = regrepeat(scan, n);
                locinput = PL_reginput;
                if (ln < n && PL_regkind[(U8)OP(next)] == EOL &&
-                   (!PL_multiline  || OP(next) == SEOL || OP(next) == EOS)) {
+                   (OP(next) != MEOL ||
+                       OP(next) == SEOL || OP(next) == EOS))
+               {
                    ln = n;                     /* why back off? */
                    /* ...because $ and \Z can match before *and* after
                       newline at the end.  Consider "\n\n" =~ /\n+\Z\n/.
@@ -3575,12 +3753,15 @@ S_regmatch(pTHX_ regnode *prog)
                    while (n >= ln) {
                        if (c1 != -1000) {
                            if (do_utf8)
-                               c = utf8_to_uvchr((U8*)PL_reginput, NULL);
+                               c = utf8n_to_uvchr((U8*)PL_reginput,
+                                                  UTF8_MAXLEN, 0,
+                                                  ckWARN(WARN_UTF8) ?
+                                                  0 : UTF8_ALLOW_ANY);
                            else
                                c = UCHARAT(PL_reginput);
                        }
                        /* If it could work, try it. */
-                       if (c1 == -1000 || c == c1 || c == c2)
+                       if (c1 == -1000 || c == (UV)c1 || c == (UV)c2)
                            {
                                TRYPAREN(paren, n, PL_reginput);
                                REGCP_UNWIND(lastcp);
@@ -3595,12 +3776,15 @@ S_regmatch(pTHX_ regnode *prog)
                    while (n >= ln) {
                        if (c1 != -1000) {
                            if (do_utf8)
-                               c = utf8_to_uvchr((U8*)PL_reginput, NULL);
+                               c = utf8n_to_uvchr((U8*)PL_reginput,
+                                                  UTF8_MAXLEN, 0,
+                                                  ckWARN(WARN_UTF8) ?
+                                                  0 : UTF8_ALLOW_ANY);
                            else
                                c = UCHARAT(PL_reginput);
                        }
                        /* If it could work, try it. */
-                       if (c1 == -1000 || c == c1 || c == c2)
+                       if (c1 == -1000 || c == (UV)c1 || c == (UV)c2)
                            {
                                TRYPAREN(paren, n, PL_reginput);
                                REGCP_UNWIND(lastcp);
@@ -3676,6 +3860,7 @@ S_regmatch(pTHX_ regnode *prog)
            }
            else
                PL_reginput = locinput;
+           PL_reg_flags ^= RF_false;
            goto do_ifmatch;
        case IFMATCH:
            n = 1;
@@ -3691,6 +3876,8 @@ S_regmatch(pTHX_ regnode *prog)
          do_ifmatch:
            inner = NEXTOPER(NEXTOPER(scan));
            if (regmatch(inner) != n) {
+               if (n == 0)
+                   PL_reg_flags ^= RF_false;
              say_no:
                if (logical) {
                    logical = 0;
@@ -3700,6 +3887,8 @@ S_regmatch(pTHX_ regnode *prog)
                else
                    sayNO;
            }
+           if (n == 0)
+               PL_reg_flags ^= RF_false;
          say_yes:
            if (logical) {
                logical = 0;
@@ -3836,7 +4025,9 @@ S_regrepeat(pTHX_ regnode *p, I32 max)
     register bool do_utf8 = PL_reg_match_utf8;
 
     scan = PL_reginput;
-    if (max != REG_INFTY && max < loceol - scan)
+    if (max == REG_INFTY)
+       max = I32_MAX;
+    else if (max < loceol - scan)
       loceol = scan + max;
     switch (OP(p)) {
     case REG_ANY:
@@ -3852,7 +4043,15 @@ S_regrepeat(pTHX_ regnode *p, I32 max)
        }
        break;
     case SANY:
-       scan = loceol;
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (scan < loceol && hardcount < max) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       }
+       else
+           scan = loceol;
        break;
     case CANY:
        scan = loceol;
@@ -3879,12 +4078,12 @@ S_regrepeat(pTHX_ regnode *p, I32 max)
        if (do_utf8) {
            loceol = PL_regeol;
            while (hardcount < max && scan < loceol &&
-                  reginclass(p, (U8*)scan, do_utf8)) {
+                  reginclass(p, (U8*)scan, 0, do_utf8)) {
                scan += UTF8SKIP(scan);
                hardcount++;
            }
        } else {
-           while (scan < loceol && reginclass(p, (U8*)scan, do_utf8))
+           while (scan < loceol && REGINCLASS(p, (U8*)scan))
                scan++;
        }
        break;
@@ -4056,7 +4255,7 @@ S_regrepeat(pTHX_ regnode *p, I32 max)
 /*
  - regrepeat_hard - repeatedly match something, report total lenth and length
  *
- * The repeater is supposed to have constant length.
+ * The repeater is supposed to have constant non-zero length.
  */
 
 STATIC I32
@@ -4110,10 +4309,11 @@ S_regrepeat_hard(pTHX_ regnode *p, I32 max, I32 *lp)
 */
 
 SV *
-Perl_regclass_swash(pTHX_ register regnode* node, bool doinit, SV** initsvp)
+Perl_regclass_swash(pTHX_ register regnode* node, bool doinit, SV** listsvp, SV **altsvp)
 {
-    SV *sw = NULL;
-    SV *si = NULL;
+    SV *sw  = NULL;
+    SV *si  = NULL;
+    SV *alt = NULL;
 
     if (PL_regdata && PL_regdata->count) {
        U32 n = ARG(node);
@@ -4121,41 +4321,62 @@ Perl_regclass_swash(pTHX_ register regnode* node, bool doinit, SV** initsvp)
        if (PL_regdata->what[n] == 's') {
            SV *rv = (SV*)PL_regdata->data[n];
            AV *av = (AV*)SvRV((SV*)rv);
-           SV **a;
-       
-           si = *av_fetch(av, 0, FALSE);
-           a  =  av_fetch(av, 1, FALSE);
+           SV **ary = AvARRAY(av);
+           SV **a, **b;
        
+           /* See the end of regcomp.c:S_reglass() for
+            * documentation of these array elements. */
+
+           si = *ary;
+           a  = SvTYPE(ary[1]) == SVt_RV   ? &ary[1] : 0;
+           b  = SvTYPE(ary[2]) == SVt_PVAV ? &ary[2] : 0;
+
            if (a)
                sw = *a;
            else if (si && doinit) {
                sw = swash_init("utf8", "", si, 1, 0);
                (void)av_store(av, 1, sw);
            }
+           if (b)
+               alt = *b;
        }
     }
        
-    if (initsvp)
-       *initsvp = si;
+    if (listsvp)
+       *listsvp = si;
+    if (altsvp)
+       *altsvp  = alt;
 
     return sw;
 }
 
 /*
  - reginclass - determine if a character falls into a character class
+  The n is the ANYOF regnode, the p is the target string, lenp
+  is pointer to the maximum length of how far to go in the p
+  (if the lenp is zero, UTF8SKIP(p) is used),
+  do_utf8 tells whether the target string is in UTF-8.
+
  */
 
 STATIC bool
-S_reginclass(pTHX_ register regnode *n, register U8* p, register bool do_utf8)
+S_reginclass(pTHX_ register regnode *n, register U8* p, STRLEN* lenp, register bool do_utf8)
 {
     char flags = ANYOF_FLAGS(n);
     bool match = FALSE;
-    UV c;
+    UV c = *p;
     STRLEN len = 0;
+    STRLEN plen;
 
-    c = do_utf8 ? utf8_to_uvchr(p, &len) : *p;
+    if (do_utf8 && !UTF8_IS_INVARIANT(c))
+        c = utf8n_to_uvchr(p, UTF8_MAXLEN, &len,
+                           ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY);
 
+    plen = lenp ? *lenp : UNISKIP(NATIVE_TO_UNI(c));
     if (do_utf8 || (flags & ANYOF_UNICODE)) {
+        if (lenp)
+           *lenp = 0;
        if (do_utf8 && !ANYOF_RUNTIME(n)) {
            if (len != (STRLEN)-1 && c < 256 && ANYOF_BITMAP_TEST(n, c))
                match = TRUE;
@@ -4163,30 +4384,47 @@ S_reginclass(pTHX_ register regnode *n, register U8* p, register bool do_utf8)
        if (!match && do_utf8 && (flags & ANYOF_UNICODE_ALL) && c >= 256)
            match = TRUE;
        if (!match) {
-           SV *sw = regclass_swash(n, TRUE, 0);
+           AV *av;
+           SV *sw = regclass_swash(n, TRUE, 0, (SV**)&av);
        
            if (sw) {
                if (swash_fetch(sw, p, do_utf8))
                    match = TRUE;
                else if (flags & ANYOF_FOLD) {
-                   U8 foldbuf[UTF8_MAXLEN_FOLD+1];
-                   STRLEN foldlen;
-
-                   to_utf8_fold(p, foldbuf, &foldlen);
-                   if (swash_fetch(sw, foldbuf, do_utf8))
-                       match = TRUE;
-                   to_utf8_upper(p, foldbuf, &foldlen);
-                   if (swash_fetch(sw, foldbuf, do_utf8))
-                       match = TRUE;
+                   if (!match && lenp && av) {
+                       I32 i;
+                     
+                       for (i = 0; i <= av_len(av); i++) {
+                           SV* sv = *av_fetch(av, i, FALSE);
+                           STRLEN len;
+                           char *s = SvPV(sv, len);
+                       
+                           if (len <= plen && memEQ(s, (char*)p, len)) {
+                               *lenp = len;
+                               match = TRUE;
+                               break;
+                           }
+                       }
+                   }
+                   if (!match) {
+                       U8 tmpbuf[UTF8_MAXLEN_FOLD+1];
+                       STRLEN tmplen;
+
+                       to_utf8_fold(p, tmpbuf, &tmplen);
+                       if (swash_fetch(sw, tmpbuf, do_utf8))
+                           match = TRUE;
+                   }
                }
            }
        }
+       if (match && lenp && *lenp == 0)
+           *lenp = UNISKIP(NATIVE_TO_UNI(c));
     }
     if (!match && c < 256) {
        if (ANYOF_BITMAP_TEST(n, c))
            match = TRUE;
        else if (flags & ANYOF_FOLD) {
-         I32 f;
+           U8 f;
 
            if (flags & ANYOF_LOCALE) {
                PL_reg_flags |= RF_tainted;
@@ -4314,6 +4552,9 @@ restore_pos(pTHX_ void *arg)
        if (PL_reg_oldsaved) {
            PL_reg_re->subbeg = PL_reg_oldsaved;
            PL_reg_re->sublen = PL_reg_oldsavedlen;
+#ifdef PERL_COPY_ON_WRITE
+           PL_reg_re->saved_copy = PL_nrs;
+#endif
            RX_MATCH_COPIED_on(PL_reg_re);
        }
        PL_reg_magic->mg_len = PL_reg_oldpos;
@@ -4321,3 +4562,59 @@ restore_pos(pTHX_ void *arg)
        PL_curpm = PL_reg_oldcurpm;
     }  
 }
+
+STATIC void
+S_to_utf8_substr(pTHX_ register regexp *prog)
+{
+    SV* sv;
+    if (prog->float_substr && !prog->float_utf8) {
+       prog->float_utf8 = sv = NEWSV(117, 0);
+       SvSetSV(sv, prog->float_substr);
+       sv_utf8_upgrade(sv);
+       if (SvTAIL(prog->float_substr))
+           SvTAIL_on(sv);
+       if (prog->float_substr == prog->check_substr)
+           prog->check_utf8 = sv;
+    }
+    if (prog->anchored_substr && !prog->anchored_utf8) {
+       prog->anchored_utf8 = sv = NEWSV(118, 0);
+       SvSetSV(sv, prog->anchored_substr);
+       sv_utf8_upgrade(sv);
+       if (SvTAIL(prog->anchored_substr))
+           SvTAIL_on(sv);
+       if (prog->anchored_substr == prog->check_substr)
+           prog->check_utf8 = sv;
+    }
+}
+
+STATIC void
+S_to_byte_substr(pTHX_ register regexp *prog)
+{
+    SV* sv;
+    if (prog->float_utf8 && !prog->float_substr) {
+       prog->float_substr = sv = NEWSV(117, 0);
+       SvSetSV(sv, prog->float_utf8);
+       if (sv_utf8_downgrade(sv, TRUE)) {
+           if (SvTAIL(prog->float_utf8))
+               SvTAIL_on(sv);
+       } else {
+           SvREFCNT_dec(sv);
+           prog->float_substr = sv = &PL_sv_undef;
+       }
+       if (prog->float_utf8 == prog->check_utf8)
+           prog->check_substr = sv;
+    }
+    if (prog->anchored_utf8 && !prog->anchored_substr) {
+       prog->anchored_substr = sv = NEWSV(118, 0);
+       SvSetSV(sv, prog->anchored_utf8);
+       if (sv_utf8_downgrade(sv, TRUE)) {
+           if (SvTAIL(prog->anchored_utf8))
+               SvTAIL_on(sv);
+       } else {
+           SvREFCNT_dec(sv);
+           prog->anchored_substr = sv = &PL_sv_undef;
+       }
+       if (prog->anchored_utf8 == prog->check_utf8)
+           prog->check_substr = sv;
+    }
+}