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Re: regexp trie fails compile on VMS
[perl5.git] / regexec.c
index 55cc437..fb455a6 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) 1991-2002, Larry Wall
+ ****    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
+ ****    2000, 2001, 2002, 2003, 2004, 2005, by Larry Wall and others
  ****
  ****    You may distribute under the terms of either the GNU General Public
  ****    License or the Artistic License, as specified in the README file.
 #define 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)) { ENTER; save_re_context(); (void)CAT2(is_utf8_, a)((U8*)b); LEAVE; } } STMT_END
+#define LOAD_UTF8_CHARCLASS(a,b) STMT_START { if (!CAT2(PL_utf8_,a)) { ENTER; save_re_context(); (void)CAT2(is_utf8_, a)((const U8*)b); LEAVE; } } STMT_END
 
 /* for use after a quantifier and before an EXACT-like node -- japhy */
 #define JUMPABLE(rn) ( \
@@ -171,7 +183,7 @@ 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]);
@@ -194,11 +206,11 @@ S_regcppush(pTHX_ I32 parenfloor)
 }
 
 /* These are needed since we do not localize EVAL nodes: */
-#  define REGCP_SET(cp)  DEBUG_r(PerlIO_printf(Perl_debug_log,         \
+#  define REGCP_SET(cp)  DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,         \
                             "  Setting an EVAL scope, savestack=%"IVdf"\n",    \
                             (IV)PL_savestack_ix)); cp = PL_savestack_ix
 
-#  define REGCP_UNWIND(cp)  DEBUG_r(cp != PL_savestack_ix ?            \
+#  define REGCP_UNWIND(cp)  DEBUG_EXECUTE_r(cp != PL_savestack_ix ?            \
                                PerlIO_printf(Perl_debug_log,           \
                                "  Clearing an EVAL scope, savestack=%"IVdf"..%"IVdf"\n", \
                                (IV)(cp), (IV)PL_savestack_ix) : 0); regcpblow(cp)
@@ -211,6 +223,8 @@ S_regcppop(pTHX)
     char *input;
     I32 tmps;
 
+    GET_RE_DEBUG_FLAGS_DECL;
+
     /* Pop REGCP_OTHER_ELEMS before the parentheses loop starts. */
     i = SSPOPINT;
     assert(i == SAVEt_REGCONTEXT); /* Check that the magic cookie is there. */
@@ -229,7 +243,7 @@ S_regcppop(pTHX)
        tmps = SSPOPINT;
        if (paren <= *PL_reglastparen)
            PL_regendp[paren] = tmps;
-       DEBUG_r(
+       DEBUG_EXECUTE_r(
            PerlIO_printf(Perl_debug_log,
                          "     restoring \\%"UVuf" to %"IVdf"(%"IVdf")..%"IVdf"%s\n",
                          (UV)paren, (IV)PL_regstartp[paren],
@@ -238,7 +252,7 @@ S_regcppop(pTHX)
                          (paren > *PL_reglastparen ? "(no)" : ""));
        );
     }
-    DEBUG_r(
+    DEBUG_EXECUTE_r(
        if ((I32)(*PL_reglastparen + 1) <= PL_regnpar) {
            PerlIO_printf(Perl_debug_log,
                          "     restoring \\%"IVdf"..\\%"IVdf" to undef\n",
@@ -396,18 +410,23 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
     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
 
+    GET_RE_DEBUG_FLAGS_DECL;
+
+    RX_MATCH_UTF8_set(prog,do_utf8);
+
     if (prog->reganch & ROPT_UTF8) {
-       DEBUG_r(PerlIO_printf(Perl_debug_log,
+       DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                              "UTF-8 regex...\n"));
        PL_reg_flags |= RF_utf8;
     }
 
-    DEBUG_r({
+    DEBUG_EXECUTE_r({
         char *s   = PL_reg_match_utf8 ?
                         sv_uni_display(dsv, sv, 60, UNI_DISPLAY_REGEX) :
                         strpos;
@@ -416,7 +435,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
         if (!PL_colorset)
              reginitcolors();
         if (PL_reg_match_utf8)
-            DEBUG_r(PerlIO_printf(Perl_debug_log,
+            DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                                   "UTF-8 target...\n"));
         PerlIO_printf(Perl_debug_log,
                       "%sGuessing start of match, REx%s `%s%.60s%s%s' against `%s%.*s%s%s'...\n",
@@ -433,7 +452,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *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,
+       DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                              "String too short... [re_intuit_start]\n"));
        goto fail;
     }
@@ -449,14 +468,14 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
        check = prog->check_substr;
     }
    if (check == &PL_sv_undef) {
-       DEBUG_r(PerlIO_printf(Perl_debug_log,
+       DEBUG_EXECUTE_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 */
@@ -464,7 +483,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
               /* SvCUR is not set on references: SvRV and SvPVX overlap */
               && sv && !SvROK(sv)
               && (strpos != strbeg)) {
-             DEBUG_r(PerlIO_printf(Perl_debug_log, "Not at start...\n"));
+             DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Not at start...\n"));
              goto fail;
          }
          if (prog->check_offset_min == prog->check_offset_max &&
@@ -478,7 +497,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
 
                if ( strend - s > slen || strend - s < slen - 1
                     || (strend - s == slen && strend[-1] != '\n')) {
-                   DEBUG_r(PerlIO_printf(Perl_debug_log, "String too long...\n"));
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "String too long...\n"));
                    goto fail_finish;
                }
                /* Now should match s[0..slen-2] */
@@ -487,7 +506,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                             || (slen > 1
                                 && memNE(SvPVX(check), s, slen)))) {
                  report_neq:
-                   DEBUG_r(PerlIO_printf(Perl_debug_log, "String not equal...\n"));
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "String not equal...\n"));
                    goto fail_finish;
                }
            }
@@ -541,22 +560,25 @@ 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",
+    DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%s %s substr `%s%.*s%s'%s%s",
                          (s ? "Found" : "Did not find"),
                          (check == (do_utf8 ? prog->anchored_utf8 : prog->anchored_substr) ? "anchored" : "floating"),
                          PL_colors[0],
@@ -571,7 +593,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
     check_at = s;
 
     /* Finish the diagnostic message */
-    DEBUG_r(PerlIO_printf(Perl_debug_log, "%ld...\n", (long)(s - i_strpos)) );
+    DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%ld...\n", (long)(s - i_strpos)) );
 
     /* Got a candidate.  Check MBOL anchoring, and the *other* substr.
        Start with the other substr.
@@ -595,7 +617,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
 
                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 */;
@@ -612,7 +634,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                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 */
+                   DEBUG_EXECUTE_r(must = prog->anchored_utf8);        /* for debug */
                }
                else
                    s = fbm_instr(
@@ -620,9 +642,9 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                        HOP3(HOP3(last1, prog->anchored_offset, strend)
                                + SvCUR(must), -(SvTAIL(must)!=0), strbeg),
                        must,
-                       PL_multiline ? FBMrf_MULTILINE : 0
+                       multiline ? FBMrf_MULTILINE : 0
                    );
-               DEBUG_r(PerlIO_printf(Perl_debug_log,
+               DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                        "%s anchored substr `%s%.*s%s'%s",
                        (s ? "Found" : "Contradicts"),
                        PL_colors[0],
@@ -632,11 +654,11 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                          PL_colors[1], (SvTAIL(must) ? "$" : "")));
                if (!s) {
                    if (last1 >= last2) {
-                       DEBUG_r(PerlIO_printf(Perl_debug_log,
+                       DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                                                ", giving up...\n"));
                        goto fail_finish;
                    }
-                   DEBUG_r(PerlIO_printf(Perl_debug_log,
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                        ", trying floating at offset %ld...\n",
                        (long)(HOP3c(s1, 1, strend) - i_strpos)));
                    other_last = HOP3c(last1, prog->anchored_offset+1, strend);
@@ -644,7 +666,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                    goto restart;
                }
                else {
-                   DEBUG_r(PerlIO_printf(Perl_debug_log, " at offset %ld...\n",
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, " at offset %ld...\n",
                          (long)(s - i_strpos)));
                    t = HOP3c(s, -prog->anchored_offset, strbeg);
                    other_last = HOP3c(s, 1, strend);
@@ -675,14 +697,14 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
               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 */
+               DEBUG_EXECUTE_r(must = prog->float_utf8);       /* for debug message */
            }
            else
                s = fbm_instr((unsigned char*)s,
                              (unsigned char*)last + SvCUR(must)
                                  - (SvTAIL(must)!=0),
-                             must, PL_multiline ? FBMrf_MULTILINE : 0);
-           DEBUG_r(PerlIO_printf(Perl_debug_log, "%s floating substr `%s%.*s%s'%s",
+                             must, multiline ? FBMrf_MULTILINE : 0);
+           DEBUG_EXECUTE_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)),
@@ -690,11 +712,11 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                      PL_colors[1], (SvTAIL(must) ? "$" : "")));
            if (!s) {
                if (last1 == last) {
-                   DEBUG_r(PerlIO_printf(Perl_debug_log,
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                                            ", giving up...\n"));
                    goto fail_finish;
                }
-               DEBUG_r(PerlIO_printf(Perl_debug_log,
+               DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                    ", trying anchored starting at offset %ld...\n",
                    (long)(s1 + 1 - i_strpos)));
                other_last = last;
@@ -702,7 +724,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                goto restart;
            }
            else {
-               DEBUG_r(PerlIO_printf(Perl_debug_log, " at offset %ld...\n",
+               DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, " at offset %ld...\n",
                      (long)(s - i_strpos)));
                other_last = s; /* Fix this later. --Hugo */
                s = s1;
@@ -715,7 +737,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
 
     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
@@ -741,33 +763,33 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                               is float.  Redo checking for "other"=="fixed".
                             */
                            strpos = t + 1;                     
-                           DEBUG_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m at offset %ld, rescanning for anchored from offset %ld...\n",
+                           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m at offset %ld, rescanning for anchored from offset %ld...\n",
                                PL_colors[0],PL_colors[1], (long)(strpos - i_strpos), (long)(strpos - i_strpos + prog->anchored_offset)));
                            goto do_other_anchored;
                        }
                        /* We don't contradict the found floating substring. */
                        /* XXXX Why not check for STCLASS? */
                        s = t + 1;
-                       DEBUG_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m at offset %ld...\n",
+                       DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m at offset %ld...\n",
                            PL_colors[0],PL_colors[1], (long)(s - i_strpos)));
                        goto set_useful;
                    }
                    /* Position contradicts check-string */
                    /* XXXX probably better to look for check-string
                       than for "\n", so one should lower the limit for t? */
-                   DEBUG_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m, restarting lookup for check-string at offset %ld...\n",
+                   DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Found /%s^%s/m, restarting lookup for check-string at offset %ld...\n",
                        PL_colors[0],PL_colors[1], (long)(t + 1 - i_strpos)));
                    other_last = strpos = s = t + 1;
                    goto restart;
                }
                t++;
            }
-           DEBUG_r(PerlIO_printf(Perl_debug_log, "Did not find /%s^%s/m...\n",
+           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Did not find /%s^%s/m...\n",
                        PL_colors[0],PL_colors[1]));
            goto fail_finish;
        }
        else {
-           DEBUG_r(PerlIO_printf(Perl_debug_log, "Starting position does not contradict /%s^%s/m...\n",
+           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Starting position does not contradict /%s^%s/m...\n",
                        PL_colors[0],PL_colors[1]));
        }
        s = t;
@@ -790,7 +812,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
            t = strpos;
            goto find_anchor;
        }
-       DEBUG_r( if (ml_anch)
+       DEBUG_EXECUTE_r( if (ml_anch)
            PerlIO_printf(Perl_debug_log, "Position at offset %ld does not contradict /%s^%s/m...\n",
                        (long)(strpos - i_strpos), PL_colors[0],PL_colors[1]);
        );
@@ -807,7 +829,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
            )))
        {
            /* If flags & SOMETHING - do not do it many times on the same match */
-           DEBUG_r(PerlIO_printf(Perl_debug_log, "... Disabling check substring...\n"));
+           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "... Disabling check substring...\n"));
            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);
@@ -848,39 +870,36 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
        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
            char *what = 0;
 #endif
            if (endpos == strend) {
-               DEBUG_r( PerlIO_printf(Perl_debug_log,
+               DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
                                "Could not match STCLASS...\n") );
                goto fail;
            }
-           DEBUG_r( PerlIO_printf(Perl_debug_log,
+           DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
                                   "This position contradicts STCLASS...\n") );
            if ((prog->reganch & ROPT_ANCH) && !ml_anch)
                goto fail;
            /* Contradict one of substrings */
            if (prog->anchored_substr || prog->anchored_utf8) {
                if ((do_utf8 ? prog->anchored_utf8 : prog->anchored_substr) == check) {
-                   DEBUG_r( what = "anchored" );
+                   DEBUG_EXECUTE_r( what = "anchored" );
                  hop_and_restart:
                    s = HOP3c(t, 1, strend);
                    if (s + start_shift + end_shift > strend) {
                        /* XXXX Should be taken into account earlier? */
-                       DEBUG_r( PerlIO_printf(Perl_debug_log,
+                       DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
                                               "Could not match STCLASS...\n") );
                        goto fail;
                    }
                    if (!check)
                        goto giveup;
-                   DEBUG_r( PerlIO_printf(Perl_debug_log,
+                   DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
                                "Looking for %s substr starting at offset %ld...\n",
                                 what, (long)(s + start_shift - i_strpos)) );
                    goto restart;
@@ -892,7 +911,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                s = check_at;
                if (!check)
                    goto giveup;
-               DEBUG_r( PerlIO_printf(Perl_debug_log,
+               DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
                          "Looking for anchored substr starting at offset %ld...\n",
                          (long)(other_last - i_strpos)) );
                goto do_other_anchored;
@@ -903,7 +922,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                s = t = t + 1;
                if (!check)
                    goto giveup;
-               DEBUG_r( PerlIO_printf(Perl_debug_log,
+               DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log,
                          "Looking for /%s^%s/m starting at offset %ld...\n",
                          PL_colors[0],PL_colors[1], (long)(t - i_strpos)) );
                goto try_at_offset;
@@ -913,23 +932,23 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
            /* Check is floating subtring. */
          retry_floating_check:
            t = check_at - start_shift;
-           DEBUG_r( what = "floating" );
+           DEBUG_EXECUTE_r( what = "floating" );
            goto hop_and_restart;
        }
        if (t != s) {
-            DEBUG_r(PerlIO_printf(Perl_debug_log,
+            DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                        "By STCLASS: moving %ld --> %ld\n",
                                   (long)(t - i_strpos), (long)(s - i_strpos))
                    );
         }
         else {
-            DEBUG_r(PerlIO_printf(Perl_debug_log,
+            DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                                   "Does not contradict STCLASS...\n"); 
                    );
         }
     }
   giveup:
-    DEBUG_r(PerlIO_printf(Perl_debug_log, "%s%s:%s match at offset %ld\n",
+    DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%s%s:%s match at offset %ld\n",
                          PL_colors[4], (check ? "Guessed" : "Giving up"),
                          PL_colors[5], (long)(s - i_strpos)) );
     return s;
@@ -938,7 +957,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
     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",
+    DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%sMatch rejected by optimizer%s\n",
                          PL_colors[4],PL_colors[5]));
     return Nullch;
 }
@@ -950,6 +969,8 @@ 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;
@@ -959,25 +980,40 @@ 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) {
-               STRLEN skip = do_utf8 ? UTF8SKIP(s) : 1;
-                 
-               if (do_utf8 ?
-                   reginclass(c, (U8*)s, 0, do_utf8) :
-                   REGINCLASS(c, (U8*)s) ||
-                   (ANYOF_FOLD_SHARP_S(c, s, strend) &&
-                    /* The assignment of 2 is intentional:
-                     * for the 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;
+           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:
@@ -990,20 +1026,27 @@ 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 tmpbuf1[UTF8_MAXLEN_UCLC+1];
-               U8 tmpbuf2[UTF8_MAXLEN_UCLC+1];
+               U8 *sm = (U8 *) m;
+               U8 tmpbuf1[UTF8_MAXBYTES_CASE+1];
+               U8 tmpbuf2[UTF8_MAXBYTES_CASE+1];
 
                to_utf8_lower((U8*)m, tmpbuf1, &ulen1);
                to_utf8_upper((U8*)m, tmpbuf2, &ulen2);
 
-               c1 = utf8n_to_uvchr(tmpbuf1, UTF8_MAXLEN_UCLC
+               c1 = utf8n_to_uvchr(tmpbuf1, UTF8_MAXBYTES_CASE
                                    0, ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY);
-               c2 = utf8n_to_uvchr(tmpbuf2, UTF8_MAXLEN_UCLC,
+               c2 = utf8n_to_uvchr(tmpbuf2, UTF8_MAXBYTES_CASE,
                                    0, ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY);
+               lnc = 0;
+               while (sm < ((U8 *) m + ln)) {
+                   lnc++;
+                   sm += UTF8SKIP(sm);
+               }
            }
            else {
                c1 = *(U8*)m;
@@ -1011,12 +1054,13 @@ 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 = HOP3c(strend, -(I32)ln, s);
+           e = HOP3c(strend, -((I32)lnc), s);
 
            if (norun && e < s)
                e = s;                  /* Due to minlen logic of intuit() */
@@ -1034,13 +1078,15 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
 
            if (do_utf8) {
                UV c, f;
-               U8 tmpbuf [UTF8_MAXLEN+1];
-               U8 foldbuf[UTF8_MAXLEN_FOLD+1];
+               U8 tmpbuf [UTF8_MAXBYTES+1];
+               U8 foldbuf[UTF8_MAXBYTES_CASE+1];
                STRLEN len, foldlen;
                
                if (c1 == c2) {
+                   /* Upper and lower of 1st char are equal -
+                    * probably not a "letter". */
                    while (s <= e) {
-                       c = utf8n_to_uvchr((U8*)s, UTF8_MAXLEN, &len,
+                       c = utf8n_to_uvchr((U8*)s, UTF8_MAXBYTES, &len,
                                           ckWARN(WARN_UTF8) ?
                                           0 : UTF8_ALLOW_ANY);
                        if ( c == c1
@@ -1067,7 +1113,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                }
                else {
                    while (s <= e) {
-                     c = utf8n_to_uvchr((U8*)s, UTF8_MAXLEN, &len,
+                     c = utf8n_to_uvchr((U8*)s, UTF8_MAXBYTES, &len,
                                           ckWARN(WARN_UTF8) ?
                                           0 : UTF8_ALLOW_ANY);
 
@@ -1143,7 +1189,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                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)))
@@ -1152,7 +1198,7 @@ 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 {
@@ -1186,14 +1232,14 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                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 {
@@ -1215,7 +1261,7 @@ 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;
@@ -1224,7 +1270,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1244,7 +1290,7 @@ 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;
@@ -1253,7 +1299,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1273,7 +1319,7 @@ 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;
@@ -1282,7 +1328,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1302,7 +1348,7 @@ 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;
@@ -1311,7 +1357,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1331,7 +1377,7 @@ 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;
@@ -1340,7 +1386,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1360,7 +1406,7 @@ 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;
@@ -1369,7 +1415,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1389,7 +1435,7 @@ 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;
@@ -1398,7 +1444,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1418,7 +1464,7 @@ 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;
@@ -1427,7 +1473,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1447,7 +1493,7 @@ 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;
@@ -1456,7 +1502,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1476,7 +1522,7 @@ 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;
@@ -1485,7 +1531,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1505,7 +1551,7 @@ 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;
@@ -1514,7 +1560,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1534,7 +1580,7 @@ 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;
@@ -1543,7 +1589,7 @@ S_find_byclass(pTHX_ regexp * prog, regnode *c, char *s, char *strend, char *sta
                    }
                    else
                        tmp = 1;
-                   s += UTF8SKIP(s);
+                   s += uskip;
                }
            }
            else {
@@ -1593,11 +1639,16 @@ 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 *dsv0 = PERL_DEBUG_PAD_ZERO(0);
     SV *dsv1 = PERL_DEBUG_PAD_ZERO(1);
 #endif
 
+    GET_RE_DEBUG_FLAGS_DECL;
+
+    RX_MATCH_UTF8_set(prog,do_utf8);
+
     PL_regcc = 0;
 
     cache_re(prog);
@@ -1613,7 +1664,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
 
     minlen = prog->minlen;
     if (strend - startpos < minlen) {
-        DEBUG_r(PerlIO_printf(Perl_debug_log,
+        DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                              "String too short [regexec_flags]...\n"));
        goto phooey;
     }
@@ -1674,12 +1725,12 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
        d.scream_pos = &scream_pos;
        s = re_intuit_start(prog, sv, s, strend, flags, &d);
        if (!s) {
-           DEBUG_r(PerlIO_printf(Perl_debug_log, "Not present...\n"));
+           DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Not present...\n"));
            goto phooey;        /* not present */
        }
     }
 
-    DEBUG_r({
+    DEBUG_EXECUTE_r({
         char *s0   = UTF ?
           pv_uni_display(dsv0, (U8*)prog->precomp, prog->prelen, 60,
                          UNI_DISPLAY_REGEX) :
@@ -1708,7 +1759,7 @@ 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;
@@ -1767,7 +1818,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
        if (do_utf8) {
            while (s < strend) {
                if (*s == ch) {
-                   DEBUG_r( did_match = 1 );
+                   DEBUG_EXECUTE_r( did_match = 1 );
                    if (regtry(prog, s)) goto got_it;
                    s += UTF8SKIP(s);
                    while (s < strend && *s == ch)
@@ -1779,7 +1830,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
        else {
            while (s < strend) {
                if (*s == ch) {
-                   DEBUG_r( did_match = 1 );
+                   DEBUG_EXECUTE_r( did_match = 1 );
                    if (regtry(prog, s)) goto got_it;
                    s++;
                    while (s < strend && *s == ch)
@@ -1788,7 +1839,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
                s++;
            }
        }
-       DEBUG_r(if (!did_match)
+       DEBUG_EXECUTE_r(if (!did_match)
                PerlIO_printf(Perl_debug_log,
                                   "Did not find anchored character...\n")
                );
@@ -1842,8 +1893,11 @@ 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))) ) {
-           DEBUG_r( did_match = 1 );
+                                 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_EXECUTE_r( did_match = 1 );
            if (HOPc(s, -back_max) > last1) {
                last1 = HOPc(s, -back_min);
                s = HOPc(s, -back_max);
@@ -1869,7 +1923,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
                }
            }
        }
-       DEBUG_r(if (!did_match)
+       DEBUG_EXECUTE_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_utf8)
@@ -1882,10 +1936,13 @@ 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));
-       DEBUG_r({
+           if (PL_regkind[op] != EXACT && op != CANY)
+               strend = HOPc(strend, -(minlen - 1));
+       }
+       DEBUG_EXECUTE_r({
            SV *prop = sv_newmortal();
            char *s0;
            char *s1;
@@ -1908,7 +1965,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
        });
        if (find_byclass(prog, c, s, strend, startpos, 0))
            goto got_it;
-       DEBUG_r(PerlIO_printf(Perl_debug_log, "Contradicts stclass...\n"));
+       DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "Contradicts stclass...\n"));
     }
     else {
        dontbother = 0;
@@ -1926,6 +1983,9 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
                                   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;
@@ -1934,7 +1994,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
                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
@@ -1948,7 +2008,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
                }
            }
            if (last == NULL) {
-               DEBUG_r(PerlIO_printf(Perl_debug_log,
+               DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                                      "%sCan't trim the tail, match fails (should not happen)%s\n",
                                      PL_colors[4],PL_colors[5]));
                goto phooey; /* Should not happen! */
@@ -1993,17 +2053,28 @@ 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;
@@ -2014,7 +2085,7 @@ got_it:
     return 1;
 
 phooey:
-    DEBUG_r(PerlIO_printf(Perl_debug_log, "%sMatch failed%s\n",
+    DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%sMatch failed%s\n",
                          PL_colors[4],PL_colors[5]));
     if (PL_reg_eval_set)
        restore_pos(aTHX_ 0);
@@ -2031,6 +2102,7 @@ S_regtry(pTHX_ regexp *prog, char *startpos)
     register I32 *sp;
     register I32 *ep;
     CHECKPOINT lastcp;
+    GET_RE_DEBUG_FLAGS_DECL;
 
 #ifdef DEBUGGING
     PL_regindent = 0;  /* XXXX Not good when matches are reenterable... */
@@ -2039,7 +2111,7 @@ S_regtry(pTHX_ regexp *prog, char *startpos)
        MAGIC *mg;
 
        PL_reg_eval_set = RS_init;
-       DEBUG_r(DEBUG_s(
+       DEBUG_EXECUTE_r(DEBUG_s(
            PerlIO_printf(Perl_debug_log, "  setting stack tmpbase at %"IVdf"\n",
                          (IV)(PL_stack_sp - PL_stack_base));
            ));
@@ -2054,8 +2126,7 @@ 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;
            }
        
@@ -2093,6 +2164,9 @@ 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
@@ -2107,8 +2181,9 @@ 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);
+    DEBUG_EXECUTE_r(PL_reg_starttry = startpos);
     if (PL_reg_start_tmpl <= prog->nparens) {
        PL_reg_start_tmpl = prog->nparens*3/2 + 3;
         if(PL_reg_start_tmp)
@@ -2189,7 +2264,113 @@ typedef union re_unwind_t {
 #define sayNO_SILENT goto do_no
 #define saySAME(x) if (x) goto yes; else goto no
 
-#define REPORT_CODE_OFF 24
+#define POSCACHE_SUCCESS 0     /* caching success rather than failure */
+#define POSCACHE_SEEN 1                /* we know what we're caching */
+#define POSCACHE_START 2       /* the real cache: this bit maps to pos 0 */
+#define CACHEsayYES STMT_START { \
+    if (PL_reg_poscache) { \
+       if (!(PL_reg_poscache[0] & (1<<POSCACHE_SEEN))) \
+           PL_reg_poscache[0] |= (1<<POSCACHE_SUCCESS) || (1<<POSCACHE_SEEN); \
+        else if (!(PL_reg_poscache[0] & (1<<POSCACHE_SUCCESS))) { \
+           /* cache records failure, but this is success */ \
+           I32 o = locinput - PL_bostr, b; \
+           o = (scan->flags & 0xf) - 1 + POSCACHE_START + o * (scan->flags>>4); \
+           b = o % 8; \
+           o /= 8; \
+           DEBUG_r( \
+               PerlIO_printf(Perl_debug_log, \
+                   "%*s  (remove success from failure cache)\n", \
+                   REPORT_CODE_OFF+PL_regindent*2, "") \
+           ); \
+           PL_reg_poscache[o] &= ~(1<<b); \
+       } \
+    } \
+    sayYES; \
+} STMT_END
+#define CACHEsayNO STMT_START { \
+    if (PL_reg_poscache) { \
+       if (!(PL_reg_poscache[0] & (1<<POSCACHE_SEEN))) \
+           PL_reg_poscache[0] |= (1<<POSCACHE_SEEN); \
+        else if ((PL_reg_poscache[0] & (1<<POSCACHE_SUCCESS))) { \
+           /* cache records success, but this is failure */ \
+           I32 o = locinput - PL_bostr, b; \
+           o = (scan->flags & 0xf) - 1 + POSCACHE_START + o * (scan->flags>>4); \
+           b = o % 8; \
+           o /= 8; \
+           DEBUG_r( \
+               PerlIO_printf(Perl_debug_log, \
+                   "%*s  (remove failure from success cache)\n", \
+                   REPORT_CODE_OFF+PL_regindent*2, "") \
+           ); \
+           PL_reg_poscache[o] &= ~(1<<b); \
+       } \
+    } \
+    sayNO; \
+} STMT_END
+
+/* this is used to determine how far from the left messages like
+   'failed...' are printed. Currently 29 makes these messages line
+   up with the opcode they refer to. Earlier perls used 25 which
+   left these messages outdented making reviewing a debug output
+   quite difficult.
+*/
+#define REPORT_CODE_OFF 29
+
+
+/* Make sure there is a test for this +1 options in re_tests */
+#define TRIE_INITAL_ACCEPT_BUFFLEN 4;
+
+#define TRIE_CHECK_STATE_IS_ACCEPTING STMT_START {                       \
+    if ( trie->states[ state ].wordnum ) {                               \
+       if ( !accepted ) {                                               \
+           ENTER;                                                       \
+           SAVETMPS;                                                    \
+           bufflen = TRIE_INITAL_ACCEPT_BUFFLEN ;                       \
+           sv_accept_buff=NEWSV( 1234,                                  \
+             bufflen * sizeof(reg_trie_accepted) - 1 );                 \
+           SvCUR_set( sv_accept_buff, sizeof(reg_trie_accepted) );      \
+           SvPOK_on( sv_accept_buff );                                  \
+           sv_2mortal( sv_accept_buff );                                \
+           accept_buff = (reg_trie_accepted*)SvPV_nolen( sv_accept_buff );\
+       } else {                                                         \
+           if ( accepted >= bufflen ) {                                 \
+               bufflen *= 2;                                            \
+               accept_buff =(reg_trie_accepted*)SvGROW( sv_accept_buff, \
+                   bufflen * sizeof(reg_trie_accepted) );               \
+           }                                                            \
+           SvCUR_set( sv_accept_buff,SvCUR( sv_accept_buff )            \
+               + sizeof( reg_trie_accepted ) );                         \
+       }                                                                \
+       accept_buff[ accepted ].wordnum = trie->states[ state ].wordnum; \
+       accept_buff[ accepted ].endpos = uc;                             \
+       ++accepted;                                                      \
+    } } STMT_END
+
+#define TRIE_HANDLE_CHAR STMT_START {                                   \
+        if ( uvc < 256 ) {                                              \
+            charid = trie->charmap[ uvc ];                              \
+        } else {                                                        \
+            charid = 0;                                                 \
+            if( trie->widecharmap ) {                                   \
+            SV** svpp = (SV**)NULL;                                     \
+            svpp = hv_fetch( trie->widecharmap, (char*)&uvc,            \
+                         sizeof( UV ), 0 );                            \
+            if ( svpp ) {                                               \
+               charid = (U16)SvIV( *svpp );                            \
+                }                                                       \
+            }                                                           \
+        }                                                               \
+        if ( charid &&                                                  \
+             ( base + charid > trie->uniquecharcount ) &&               \
+             ( base + charid - 1 - trie->uniquecharcount < trie->lasttrans) && \
+             trie->trans[ base + charid - 1 - trie->uniquecharcount ].check == state ) \
+        {                                                               \
+            state = trie->trans[ base + charid - 1 - trie->uniquecharcount ].next;     \
+        } else {                                                        \
+            state = 0;                                                  \
+        }                                                               \
+        uc += len;                                                      \
+    } STMT_END
 
 /*
  - regmatch - main matching routine
@@ -2220,6 +2401,13 @@ S_regmatch(pTHX_ regnode *prog)
     register I32 c1 = 0, c2 = 0, paren;        /* case fold search, parenth */
     int minmod = 0, sw = 0, logical = 0;
     I32 unwind = 0;
+
+    /* used by the trie code */
+    SV                 *sv_accept_buff;  /* accepting states we have traversed */
+    reg_trie_accepted  *accept_buff;     /* "" */
+    reg_trie_data      *trie;            /* what trie are we using right now */
+    U32 accepted = 0;                    /* how many accepting states we have seen*/
+
 #if 0
     I32 firstcp = PL_savestack_ix;
 #endif
@@ -2228,18 +2416,23 @@ S_regmatch(pTHX_ regnode *prog)
     SV *dsv0 = PERL_DEBUG_PAD_ZERO(0);
     SV *dsv1 = PERL_DEBUG_PAD_ZERO(1);
     SV *dsv2 = PERL_DEBUG_PAD_ZERO(2);
+
+    SV *re_debug_flags;
 #endif
 
+    GET_RE_DEBUG_FLAGS;
+
 #ifdef DEBUGGING
     PL_regindent++;
 #endif
 
+
     /* Note that nextchr is a byte even in UTF */
     nextchr = UCHARAT(locinput);
     scan = prog;
     while (scan != NULL) {
 
-        DEBUG_r( {
+        DEBUG_EXECUTE_r( {
            SV *prop = sv_newmortal();
            int docolor = *PL_colors[0];
            int taill = (docolor ? 10 : 7); /* 3 chars for "> <" */
@@ -2269,17 +2462,17 @@ 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, 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, 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, UNI_DISPLAY_REGEX) :
                locinput;
@@ -2310,8 +2503,7 @@ 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;
@@ -2333,12 +2525,8 @@ 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;
@@ -2382,6 +2570,231 @@ S_regmatch(pTHX_ regnode *prog)
            else
                nextchr = UCHARAT(++locinput);
            break;
+
+
+
+       /*
+          traverse the TRIE keeping track of all accepting states
+          we transition through until we get to a failing node.
+
+          we use two slightly different pieces of code to handle
+          the traversal depending on whether its case sensitive or
+          not. we reuse the accept code however. (this should probably
+          be turned into a macro.)
+
+       */
+       case TRIEF:
+       case TRIEFL:
+           {
+
+               U32 uniflags = ckWARN( WARN_UTF8 ) ? 0 : UTF8_ALLOW_ANY;
+               U8 *uc = ( U8* )locinput;
+               U32 state = 1;
+               U16 charid = 0;
+               U32 base = 0;
+               UV uvc = 0;
+               STRLEN len = 0;
+               STRLEN foldlen = 0;
+               U8 foldbuf[ UTF8_MAXBYTES_CASE + 1 ];
+               U8 *uscan = (U8*)NULL;
+               STRLEN bufflen=0;
+               accepted = 0;
+
+               trie = (reg_trie_data*)PL_regdata->data[ ARG( scan ) ];
+
+               while ( state && uc <= (U8*)PL_regeol ) {
+
+                   TRIE_CHECK_STATE_IS_ACCEPTING;
+
+                   base = trie->states[ state ].trans.base;
+
+                   DEBUG_TRIE_EXECUTE_r(
+                               PerlIO_printf( Perl_debug_log,
+                                   "%*s  %sState: %4x, Base: %4x Accepted: %4x ",
+                                   REPORT_CODE_OFF + PL_regindent * 2, "", PL_colors[4],
+                                   state, base, accepted );
+                   );
+
+                   if ( base ) {
+
+                       if ( do_utf8 || UTF ) {
+                           if ( foldlen>0 ) {
+                               uvc = utf8n_to_uvuni( uscan, UTF8_MAXLEN, &len, uniflags );
+                               foldlen -= len;
+                               uscan += len;
+                               len=0;
+                           } else {
+                               uvc = utf8n_to_uvuni( (U8*)uc, UTF8_MAXLEN, &len, uniflags );
+                               uvc = to_uni_fold( uvc, foldbuf, &foldlen );
+                               foldlen -= UNISKIP( uvc );
+                               uscan = foldbuf + UNISKIP( uvc );
+                           }
+                       } else {
+                           uvc = (U32)*uc;
+                           len = 1;
+                       }
+
+                       TRIE_HANDLE_CHAR;
+
+                   } else {
+                       state = 0;
+                   }
+                   DEBUG_TRIE_EXECUTE_r(
+                               PerlIO_printf( Perl_debug_log,
+                                   "Charid:%3x CV:%4x After State: %4x%s\n",
+                                   charid, uvc, state, PL_colors[5] );
+                   );
+               }
+               if ( !accepted ) {
+                  sayNO;
+               } else {
+                   goto TrieAccept;
+               }
+           }
+           /* unreached codepoint: we jump into the middle of the next case
+              from previous if blocks */
+       case TRIE:
+           {
+               U32 uniflags = ckWARN( WARN_UTF8 ) ? 0 : UTF8_ALLOW_ANY;
+               U8 *uc = (U8*)locinput;
+               U32 state = 1;
+               U16 charid = 0;
+               U32 base = 0;
+               UV uvc = 0;
+               STRLEN len = 0;
+               STRLEN bufflen = 0;
+               accepted = 0;
+
+               trie = (reg_trie_data*)PL_regdata->data[ ARG( scan ) ];
+
+               while ( state && uc <= (U8*)PL_regeol ) {
+
+                   TRIE_CHECK_STATE_IS_ACCEPTING;
+
+                   base = trie->states[ state ].trans.base;
+
+                   DEBUG_TRIE_EXECUTE_r(
+                           PerlIO_printf( Perl_debug_log,
+                               "%*s  %sState: %4x, Base: %4x Accepted: %4x ",
+                               REPORT_CODE_OFF + PL_regindent * 2, "", PL_colors[4],
+                               state, base, accepted );
+                   );
+
+                   if ( base ) {
+
+                       if ( do_utf8 || UTF ) {
+                           uvc = utf8n_to_uvuni( (U8*)uc, UTF8_MAXLEN, &len, uniflags );
+                       } else {
+                           uvc = (U32)*uc;
+                           len = 1;
+                       }
+
+                        TRIE_HANDLE_CHAR;
+
+                   } else {
+                       state = 0;
+                   }
+                   DEBUG_TRIE_EXECUTE_r(
+                           PerlIO_printf( Perl_debug_log,
+                               "Charid:%3x CV:%4x After State: %4x%s\n",
+                               charid, uvc, state, PL_colors[5] );
+                   );
+               }
+               if ( !accepted ) {
+                  sayNO;
+               }
+           }
+
+
+           /*
+              There was at least one accepting state that we
+              transitioned through. Presumably the number of accepting
+              states is going to be low, typically one or two. So we
+              simply scan through to find the one with lowest wordnum.
+              Once we find it, we swap the last state into its place
+              and decrement the size. We then try to match the rest of
+              the pattern at the point where the word ends, if we
+              succeed then we end the loop, otherwise the loop
+              eventually terminates once all of the accepting states
+              have been tried.
+           */
+       TrieAccept:
+           {
+               int gotit = 0;
+
+               if ( accepted == 1 ) {
+                   DEBUG_EXECUTE_r({
+                        SV **tmp = av_fetch( trie->words, accept_buff[ 0 ].wordnum-1, 0 );
+                               PerlIO_printf( Perl_debug_log,
+                           "%*s  %sonly one match : #%d <%s>%s\n",
+                           REPORT_CODE_OFF+PL_regindent*2, "",PL_colors[4],
+                           accept_buff[ 0 ].wordnum,
+                           tmp ? SvPV_nolen( *tmp ) : "not compiled under -Dr",
+                           PL_colors[5] );
+                   });
+                   PL_reginput = (char *)accept_buff[ 0 ].endpos;
+                   /* in this case we free tmps/leave before we call regmatch
+                      as we wont be using accept_buff again. */
+                   FREETMPS;
+                   LEAVE;
+                   gotit = regmatch( scan + NEXT_OFF( scan ) );
+               } else {
+                    DEBUG_EXECUTE_r(
+                        PerlIO_printf( Perl_debug_log,"%*s  %sgot %d possible matches%s\n",
+                            REPORT_CODE_OFF + PL_regindent * 2, "",PL_colors[4], accepted,
+                            PL_colors[5] );
+                    );
+                   while ( !gotit && accepted-- ) {
+                       U32 best = 0;
+                       U32 cur;
+                       for( cur = 1 ; cur <= accepted ; cur++ ) {
+                            DEBUG_TRIE_EXECUTE_r(
+                                       PerlIO_printf( Perl_debug_log,
+                                           "%*s  %sgot %d (%d) as best, looking at %d (%d)%s\n",
+                                           REPORT_CODE_OFF + PL_regindent * 2, "", PL_colors[4],
+                                           best, accept_buff[ best ].wordnum, cur,
+                                           accept_buff[ cur ].wordnum, PL_colors[5] );
+                            );
+
+                           if ( accept_buff[ cur ].wordnum < accept_buff[ best ].wordnum )
+                                   best = cur;
+                       }
+                       DEBUG_EXECUTE_r({
+                           SV **tmp = av_fetch( trie->words, accept_buff[ best ].wordnum - 1, 0 );
+                           PerlIO_printf( Perl_debug_log, "%*s  %strying alternation #%d <%s> at 0x%p%s\n",
+                               REPORT_CODE_OFF+PL_regindent*2, "",PL_colors[4],
+                               accept_buff[best].wordnum,
+                               tmp ? SvPV_nolen( *tmp ) : "not compiled under -Dr",scan,
+                               PL_colors[5] );
+                       });
+                       if ( best<accepted ) {
+                           reg_trie_accepted tmp = accept_buff[ best ];
+                           accept_buff[ best ] = accept_buff[ accepted ];
+                           accept_buff[ accepted ] = tmp;
+                           best = accepted;
+                       }
+                       PL_reginput = (char *)accept_buff[ best ].endpos;
+
+                        /* 
+                           as far as I can tell we only need the SAVETMPS/FREETMPS 
+                           for re's with EVAL in them but I'm leaving them in for 
+                           all until I can be sure.
+                         */
+                       SAVETMPS;
+                       gotit = regmatch( scan + NEXT_OFF( scan ) ) ;
+                       FREETMPS;
+                   }
+                   FREETMPS;
+                   LEAVE;
+               }
+               
+               if ( gotit ) {
+                   sayYES;
+               } else {
+                   sayNO;
+               }
+           }
+           /* unreached codepoint */
        case EXACT:
            s = STRING(scan);
            ln = STR_LEN(scan);
@@ -2397,7 +2810,7 @@ S_regmatch(pTHX_ regnode *prog)
                        if (l >= PL_regeol)
                             sayNO;
                        if (NATIVE_TO_UNI(*(U8*)s) !=
-                           utf8n_to_uvuni((U8*)l, UTF8_MAXLEN, &ulen,
+                           utf8n_to_uvuni((U8*)l, UTF8_MAXBYTES, &ulen,
                                           ckWARN(WARN_UTF8) ?
                                           0 : UTF8_ALLOW_ANY))
                             sayNO;
@@ -2411,7 +2824,7 @@ S_regmatch(pTHX_ regnode *prog)
                        if (l >= PL_regeol)
                            sayNO;
                        if (NATIVE_TO_UNI(*((U8*)l)) !=
-                           utf8n_to_uvuni((U8*)s, UTF8_MAXLEN, &ulen,
+                           utf8n_to_uvuni((U8*)s, UTF8_MAXBYTES, &ulen,
                                           ckWARN(WARN_UTF8) ?
                                           0 : UTF8_ALLOW_ANY))
                            sayNO;
@@ -2744,8 +3157,8 @@ S_regmatch(pTHX_ regnode *prog)
                 */
                if (OP(scan) == REFF) {
                    STRLEN ulen1, ulen2;
-                   U8 tmpbuf1[UTF8_MAXLEN_UCLC+1];
-                   U8 tmpbuf2[UTF8_MAXLEN_UCLC+1];
+                   U8 tmpbuf1[UTF8_MAXBYTES_CASE+1];
+                   U8 tmpbuf2[UTF8_MAXBYTES_CASE+1];
                    while (s < e) {
                        if (l >= PL_regeol)
                            sayNO;
@@ -2793,10 +3206,11 @@ S_regmatch(pTHX_ regnode *prog)
            COP *ocurcop = PL_curcop;
            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)) );
+           DEBUG_EXECUTE_r( PerlIO_printf(Perl_debug_log, "  re_eval 0x%"UVxf"\n", PTR2UV(PL_op)) );
            PAD_SAVE_LOCAL(old_comppad, (PAD*)PL_regdata->data[n + 2]);
            PL_regendp[0] = PL_reg_magic->mg_len = locinput - PL_bostr;
 
@@ -2822,13 +3236,17 @@ S_regmatch(pTHX_ regnode *prog)
                    re_cc_state state;
                    CHECKPOINT cp, lastcp;
                     int toggleutf;
+                   register SV *sv;
 
-                   if(SvROK(ret) || SvRMAGICAL(ret)) {
-                       SV *sv = SvROK(ret) ? SvRV(ret) : ret;
-
-                       if(SvMAGICAL(sv))
-                           mg = mg_find(sv, PERL_MAGIC_qr);
+                   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);
@@ -2845,14 +3263,15 @@ S_regmatch(pTHX_ regnode *prog)
                         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;
                        PL_regsize = osize;
                        PL_regnpar = onpar;
                    }
-                   DEBUG_r(
+                   DEBUG_EXECUTE_r(
                        PerlIO_printf(Perl_debug_log,
                                      "Entering embedded `%s%.60s%s%s'\n",
                                      PL_colors[0],
@@ -2920,8 +3339,10 @@ 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:
@@ -3076,7 +3497,7 @@ S_regmatch(pTHX_ regnode *prog)
                n = cc->cur + 1;        /* how many we know we matched */
                PL_reginput = locinput;
 
-               DEBUG_r(
+               DEBUG_EXECUTE_r(
                    PerlIO_printf(Perl_debug_log,
                                  "%*s  %ld out of %ld..%ld  cc=%"UVxf"\n",
                                  REPORT_CODE_OFF+PL_regindent*2, "",
@@ -3090,7 +3511,7 @@ S_regmatch(pTHX_ regnode *prog)
                    PL_regcc = cc->oldcc;
                    if (PL_regcc)
                        ln = PL_regcc->cur;
-                   DEBUG_r(
+                   DEBUG_EXECUTE_r(
                        PerlIO_printf(Perl_debug_log,
                           "%*s  empty match detected, try continuation...\n",
                           REPORT_CODE_OFF+PL_regindent*2, "")
@@ -3124,7 +3545,7 @@ S_regmatch(pTHX_ regnode *prog)
                    PL_reg_leftiter = PL_reg_maxiter;
                }
                if (PL_reg_leftiter-- == 0) {
-                   I32 size = (PL_reg_maxiter + 7)/8;
+                   I32 size = (PL_reg_maxiter + 7 + POSCACHE_START)/8;
                    if (PL_reg_poscache) {
                        if ((I32)PL_reg_poscache_size < size) {
                            Renew(PL_reg_poscache, size, char);
@@ -3136,7 +3557,7 @@ S_regmatch(pTHX_ regnode *prog)
                        PL_reg_poscache_size = size;
                        Newz(29, PL_reg_poscache, size, char);
                    }
-                   DEBUG_r(
+                   DEBUG_EXECUTE_r(
                        PerlIO_printf(Perl_debug_log,
              "%sDetected a super-linear match, switching on caching%s...\n",
                                      PL_colors[4], PL_colors[5])
@@ -3145,16 +3566,21 @@ S_regmatch(pTHX_ regnode *prog)
                if (PL_reg_leftiter < 0) {
                    I32 o = locinput - PL_bostr, b;
 
-                   o = (scan->flags & 0xf) - 1 + o * (scan->flags>>4);
+                   o = (scan->flags & 0xf) - 1 + POSCACHE_START + o * (scan->flags>>4);
                    b = o % 8;
                    o /= 8;
                    if (PL_reg_poscache[o] & (1<<b)) {
-                   DEBUG_r(
+                   DEBUG_EXECUTE_r(
                        PerlIO_printf(Perl_debug_log,
                                      "%*s  already tried at this position...\n",
                                      REPORT_CODE_OFF+PL_regindent*2, "")
                        );
-                       sayNO_SILENT;
+                       if (PL_reg_poscache[0] & (1<<POSCACHE_SUCCESS))
+                           /* cache records success */
+                           sayYES;
+                       else
+                           /* cache records failure */
+                           sayNO_SILENT;
                    }
                    PL_reg_poscache[o] |= (1<<b);
                }
@@ -3170,7 +3596,7 @@ S_regmatch(pTHX_ regnode *prog)
                    REGCP_SET(lastcp);
                    if (regmatch(cc->next)) {
                        regcpblow(cp);
-                       sayYES; /* All done. */
+                       CACHEsayYES;    /* All done. */
                    }
                    REGCP_UNWIND(lastcp);
                    regcppop();
@@ -3186,10 +3612,10 @@ S_regmatch(pTHX_ regnode *prog)
                                 "Complex regular subexpression recursion",
                                 REG_INFTY - 1);
                        }
-                       sayNO;
+                       CACHEsayNO;
                    }
 
-                   DEBUG_r(
+                   DEBUG_EXECUTE_r(
                        PerlIO_printf(Perl_debug_log,
                                      "%*s  trying longer...\n",
                                      REPORT_CODE_OFF+PL_regindent*2, "")
@@ -3202,13 +3628,13 @@ S_regmatch(pTHX_ regnode *prog)
                    REGCP_SET(lastcp);
                    if (regmatch(cc->scan)) {
                        regcpblow(cp);
-                       sayYES;
+                       CACHEsayYES;
                    }
                    REGCP_UNWIND(lastcp);
                    regcppop();
                    cc->cur = n - 1;
                    cc->lastloc = lastloc;
-                   sayNO;
+                   CACHEsayNO;
                }
 
                /* Prefer scan over next for maximal matching. */
@@ -3220,12 +3646,12 @@ S_regmatch(pTHX_ regnode *prog)
                    REGCP_SET(lastcp);
                    if (regmatch(cc->scan)) {
                        regcpblow(cp);
-                       sayYES;
+                       CACHEsayYES;
                    }
                    REGCP_UNWIND(lastcp);
                    regcppop();         /* Restore some previous $<digit>s? */
                    PL_reginput = locinput;
-                   DEBUG_r(
+                   DEBUG_EXECUTE_r(
                        PerlIO_printf(Perl_debug_log,
                                      "%*s  failed, try continuation...\n",
                                      REPORT_CODE_OFF+PL_regindent*2, "")
@@ -3244,13 +3670,13 @@ S_regmatch(pTHX_ regnode *prog)
                if (PL_regcc)
                    ln = PL_regcc->cur;
                if (regmatch(cc->next))
-                   sayYES;
+                   CACHEsayYES;
                if (PL_regcc)
                    PL_regcc->cur = ln;
                PL_regcc = cc;
                cc->cur = n - 1;
                cc->lastloc = lastloc;
-               sayNO;
+               CACHEsayNO;
            }
            /* NOT REACHED */
        case BRANCHJ:
@@ -3303,7 +3729,7 @@ 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 */
@@ -3322,15 +3748,6 @@ 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;
@@ -3340,19 +3757,8 @@ 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 (
-                               (I32)*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)
@@ -3367,8 +3773,7 @@ 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 ||
@@ -3399,15 +3804,8 @@ 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(
+               DEBUG_EXECUTE_r(
                    PerlIO_printf(Perl_debug_log,
                                  "%*s  matched %"IVdf" times, len=%"IVdf"...\n",
                                  (int)(REPORT_CODE_OFF+PL_regindent*2), "",
@@ -3422,19 +3820,8 @@ 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 (
-                                   (I32)*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); }
 
@@ -3457,7 +3844,7 @@ S_regmatch(pTHX_ regnode *prog)
                        UCHARAT(PL_reginput) == c1 ||
                        UCHARAT(PL_reginput) == c2)
                    {
-                       DEBUG_r(
+                       DEBUG_EXECUTE_r(
                                PerlIO_printf(Perl_debug_log,
                                              "%*s  trying tail with n=%"IVdf"...\n",
                                              (int)(REPORT_CODE_OFF+PL_regindent*2), "", (IV)n)
@@ -3531,19 +3918,8 @@ 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 (
-                           (I32)*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); }
 
@@ -3557,21 +3933,21 @@ S_regmatch(pTHX_ regnode *prog)
                    else { /* UTF */
                        if (OP(text_node) == EXACTF || OP(text_node) == REFF) {
                             STRLEN ulen1, ulen2;
-                            U8 tmpbuf1[UTF8_MAXLEN_UCLC+1];
-                            U8 tmpbuf2[UTF8_MAXLEN_UCLC+1];
+                            U8 tmpbuf1[UTF8_MAXBYTES_CASE+1];
+                            U8 tmpbuf2[UTF8_MAXBYTES_CASE+1];
 
                             to_utf8_lower((U8*)s, tmpbuf1, &ulen1);
                             to_utf8_upper((U8*)s, tmpbuf2, &ulen2);
 
-                            c1 = utf8n_to_uvuni(tmpbuf1, UTF8_MAXLEN, 0,
+                            c1 = utf8n_to_uvuni(tmpbuf1, UTF8_MAXBYTES, 0,
                                                 ckWARN(WARN_UTF8) ?
                                                 0 : UTF8_ALLOW_ANY);
-                            c2 = utf8n_to_uvuni(tmpbuf2, UTF8_MAXLEN, 0,
+                            c2 = utf8n_to_uvuni(tmpbuf2, UTF8_MAXBYTES, 0,
                                                 ckWARN(WARN_UTF8) ?
                                                 0 : UTF8_ALLOW_ANY);
                        }
                        else {
-                           c2 = c1 = utf8n_to_uvchr(s, UTF8_MAXLEN, 0,
+                           c2 = c1 = utf8n_to_uvchr(s, UTF8_MAXBYTES, 0,
                                                     ckWARN(WARN_UTF8) ?
                                                     0 : UTF8_ALLOW_ANY);
                        }
@@ -3633,7 +4009,7 @@ S_regmatch(pTHX_ regnode *prog)
                                 * utf8_distance(old, locinput) */
                                while (locinput <= e &&
                                       utf8n_to_uvchr((U8*)locinput,
-                                                     UTF8_MAXLEN, &len,
+                                                     UTF8_MAXBYTES, &len,
                                                      ckWARN(WARN_UTF8) ?
                                                      0 : UTF8_ALLOW_ANY) != (UV)c1) {
                                    locinput += len;
@@ -3644,7 +4020,7 @@ S_regmatch(pTHX_ regnode *prog)
                                 * utf8_distance(old, locinput) */
                                while (locinput <= e) {
                                    UV c = utf8n_to_uvchr((U8*)locinput,
-                                                         UTF8_MAXLEN, &len,
+                                                         UTF8_MAXBYTES, &len,
                                                          ckWARN(WARN_UTF8) ?
                                                          0 : UTF8_ALLOW_ANY);
                                    if (c == (UV)c1 || c == (UV)c2)
@@ -3681,7 +4057,7 @@ S_regmatch(pTHX_ regnode *prog)
                    if (c1 != -1000) {
                        if (do_utf8)
                            c = utf8n_to_uvchr((U8*)PL_reginput,
-                                              UTF8_MAXLEN, 0,
+                                              UTF8_MAXBYTES, 0,
                                               ckWARN(WARN_UTF8) ?
                                               0 : UTF8_ALLOW_ANY);
                        else
@@ -3714,7 +4090,7 @@ 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) != MEOL) ||
+                   (OP(next) != MEOL ||
                        OP(next) == SEOL || OP(next) == EOS))
                {
                    ln = n;                     /* why back off? */
@@ -3731,7 +4107,7 @@ S_regmatch(pTHX_ regnode *prog)
                        if (c1 != -1000) {
                            if (do_utf8)
                                c = utf8n_to_uvchr((U8*)PL_reginput,
-                                                  UTF8_MAXLEN, 0,
+                                                  UTF8_MAXBYTES, 0,
                                                   ckWARN(WARN_UTF8) ?
                                                   0 : UTF8_ALLOW_ANY);
                            else
@@ -3754,7 +4130,7 @@ S_regmatch(pTHX_ regnode *prog)
                        if (c1 != -1000) {
                            if (do_utf8)
                                c = utf8n_to_uvchr((U8*)PL_reginput,
-                                                  UTF8_MAXLEN, 0,
+                                                  UTF8_MAXBYTES, 0,
                                                   ckWARN(WARN_UTF8) ?
                                                   0 : UTF8_ALLOW_ANY);
                            else
@@ -3802,7 +4178,7 @@ S_regmatch(pTHX_ regnode *prog)
                PL_reg_re = re;
                cache_re(re);
 
-               DEBUG_r(
+               DEBUG_EXECUTE_r(
                    PerlIO_printf(Perl_debug_log,
                                  "%*s  continuation failed...\n",
                                  REPORT_CODE_OFF+PL_regindent*2, "")
@@ -3810,7 +4186,7 @@ S_regmatch(pTHX_ regnode *prog)
                sayNO_SILENT;
            }
            if (locinput < PL_regtill) {
-               DEBUG_r(PerlIO_printf(Perl_debug_log,
+               DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                                      "%sMatch possible, but length=%ld is smaller than requested=%ld, failing!%s\n",
                                      PL_colors[4],
                                      (long)(locinput - PL_reg_starttry),
@@ -3895,14 +4271,14 @@ S_regmatch(pTHX_ regnode *prog)
     sayNO;
 
 yes_loud:
-    DEBUG_r(
+    DEBUG_EXECUTE_r(
        PerlIO_printf(Perl_debug_log,
                      "%*s  %scould match...%s\n",
                      REPORT_CODE_OFF+PL_regindent*2, "", PL_colors[4],PL_colors[5])
        );
     goto yes;
 yes_final:
-    DEBUG_r(PerlIO_printf(Perl_debug_log, "%sMatch successful!%s\n",
+    DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%sMatch successful!%s\n",
                          PL_colors[4],PL_colors[5]));
 yes:
 #ifdef DEBUGGING
@@ -3916,7 +4292,7 @@ yes:
     return 1;
 
 no:
-    DEBUG_r(
+    DEBUG_EXECUTE_r(
        PerlIO_printf(Perl_debug_log,
                      "%*s  %sfailed...%s\n",
                      REPORT_CODE_OFF+PL_regindent*2, "",PL_colors[4],PL_colors[5])
@@ -4211,15 +4587,17 @@ S_regrepeat(pTHX_ regnode *p, I32 max)
        c = scan - PL_reginput;
     PL_reginput = scan;
 
-    DEBUG_r(
-       {
+    DEBUG_r({
+               SV *re_debug_flags;
                SV *prop = sv_newmortal();
-
+                GET_RE_DEBUG_FLAGS;
+                DEBUG_EXECUTE_r({
                regprop(prop, p);
                PerlIO_printf(Perl_debug_log,
                              "%*s  %s can match %"IVdf" times out of %"IVdf"...\n",
                              REPORT_CODE_OFF+1, "", SvPVX(prop),(IV)c,(IV)max);
        });
+       });
 
     return(c);
 }
@@ -4227,7 +4605,7 @@ 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
@@ -4342,7 +4720,7 @@ S_reginclass(pTHX_ register regnode *n, register U8* p, STRLEN* lenp, register b
     STRLEN plen;
 
     if (do_utf8 && !UTF8_IS_INVARIANT(c))
-        c = utf8n_to_uvchr(p, UTF8_MAXLEN, &len,
+        c = utf8n_to_uvchr(p, UTF8_MAXBYTES, &len,
                            ckWARN(WARN_UTF8) ? 0 : UTF8_ALLOW_ANY);
 
     plen = lenp ? *lenp : UNISKIP(NATIVE_TO_UNI(c));
@@ -4379,7 +4757,7 @@ S_reginclass(pTHX_ register regnode *n, register U8* p, STRLEN* lenp, register b
                        }
                    }
                    if (!match) {
-                       U8 tmpbuf[UTF8_MAXLEN_FOLD+1];
+                       U8 tmpbuf[UTF8_MAXBYTES_CASE+1];
                        STRLEN tmplen;
 
                        to_utf8_fold(p, tmpbuf, &tmplen);
@@ -4524,6 +4902,9 @@ 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;
@@ -4537,8 +4918,7 @@ 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);
+       prog->float_utf8 = sv = newSVsv(prog->float_substr);
        sv_utf8_upgrade(sv);
        if (SvTAIL(prog->float_substr))
            SvTAIL_on(sv);
@@ -4546,8 +4926,7 @@ S_to_utf8_substr(pTHX_ register regexp *prog)
            prog->check_utf8 = sv;
     }
     if (prog->anchored_substr && !prog->anchored_utf8) {
-       prog->anchored_utf8 = sv = NEWSV(118, 0);
-       SvSetSV(sv, prog->anchored_substr);
+       prog->anchored_utf8 = sv = newSVsv(prog->anchored_substr);
        sv_utf8_upgrade(sv);
        if (SvTAIL(prog->anchored_substr))
            SvTAIL_on(sv);
@@ -4561,8 +4940,7 @@ 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);
+       prog->float_substr = sv = newSVsv(prog->float_utf8);
        if (sv_utf8_downgrade(sv, TRUE)) {
            if (SvTAIL(prog->float_utf8))
                SvTAIL_on(sv);
@@ -4574,8 +4952,7 @@ S_to_byte_substr(pTHX_ register regexp *prog)
            prog->check_substr = sv;
     }
     if (prog->anchored_utf8 && !prog->anchored_substr) {
-       prog->anchored_substr = sv = NEWSV(118, 0);
-       SvSetSV(sv, prog->anchored_utf8);
+       prog->anchored_substr = sv = newSVsv(prog->anchored_utf8);
        if (sv_utf8_downgrade(sv, TRUE)) {
            if (SvTAIL(prog->anchored_utf8))
                SvTAIL_on(sv);