This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
Signedness nit, found by Jarkko
[perl5.git] / regexec.c
index 6c82ba7..0b0cc6c 100644 (file)
--- a/regexec.c
+++ b/regexec.c
 /* TODO: Combine JUMPABLE and HAS_TEXT to cache OP(rn) */
 
 /* for use after a quantifier and before an EXACT-like node -- japhy */
-#define JUMPABLE(rn) ( \
-    OP(rn) == OPEN || OP(rn) == CLOSE || OP(rn) == EVAL || \
+/* it would be nice to rework regcomp.sym to generate this stuff. sigh */
+#define JUMPABLE(rn) (      \
+    OP(rn) == OPEN ||       \
+    (OP(rn) == CLOSE && (!cur_eval || cur_eval->u.eval.close_paren != ARG(rn))) || \
+    OP(rn) == EVAL ||   \
     OP(rn) == SUSPEND || OP(rn) == IFMATCH || \
     OP(rn) == PLUS || OP(rn) == MINMOD || \
     OP(rn) == KEEPS || (PL_regkind[OP(rn)] == VERB) || \
@@ -181,25 +184,24 @@ S_regcppush(pTHX_ I32 parenfloor)
     if (paren_elems_to_push < 0)
        Perl_croak(aTHX_ "panic: paren_elems_to_push < 0");
 
-#define REGCP_OTHER_ELEMS 8
+#define REGCP_OTHER_ELEMS 7
     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]);
-       SSPUSHINT(PL_regstartp[p]);
+       SSPUSHINT(PL_regoffs[p].end);
+       SSPUSHINT(PL_regoffs[p].start);
        SSPUSHPTR(PL_reg_start_tmp[p]);
        SSPUSHINT(p);
-       DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
+       DEBUG_BUFFERS_r(PerlIO_printf(Perl_debug_log,
          "     saving \\%"UVuf" %"IVdf"(%"IVdf")..%"IVdf"\n",
-                     (UV)p, (IV)PL_regstartp[p],
+                     (UV)p, (IV)PL_regoffs[p].start,
                      (IV)(PL_reg_start_tmp[p] - PL_bostr),
-                     (IV)PL_regendp[p]
+                     (IV)PL_regoffs[p].end
        ));
     }
 /* REGCP_OTHER_ELEMS are pushed in any case, parentheses or no. */
-    SSPUSHPTR(PL_regstartp);
-    SSPUSHPTR(PL_regendp);
+    SSPUSHPTR(PL_regoffs);
     SSPUSHINT(PL_regsize);
     SSPUSHINT(*PL_reglastparen);
     SSPUSHINT(*PL_reglastcloseparen);
@@ -246,8 +248,7 @@ S_regcppop(pTHX_ const regexp *rex)
     *PL_reglastcloseparen = SSPOPINT;
     *PL_reglastparen = SSPOPINT;
     PL_regsize = SSPOPINT;
-    PL_regendp=(I32 *) SSPOPPTR;
-    PL_regstartp=(I32 *) SSPOPPTR;
+    PL_regoffs=(regexp_paren_pair *) SSPOPPTR;
 
     
     /* Now restore the parentheses context. */
@@ -256,20 +257,20 @@ S_regcppop(pTHX_ const regexp *rex)
        I32 tmps;
        U32 paren = (U32)SSPOPINT;
        PL_reg_start_tmp[paren] = (char *) SSPOPPTR;
-       PL_regstartp[paren] = SSPOPINT;
+       PL_regoffs[paren].start = SSPOPINT;
        tmps = SSPOPINT;
        if (paren <= *PL_reglastparen)
-           PL_regendp[paren] = tmps;
-       DEBUG_EXECUTE_r(
+           PL_regoffs[paren].end = tmps;
+       DEBUG_BUFFERS_r(
            PerlIO_printf(Perl_debug_log,
                          "     restoring \\%"UVuf" to %"IVdf"(%"IVdf")..%"IVdf"%s\n",
-                         (UV)paren, (IV)PL_regstartp[paren],
+                         (UV)paren, (IV)PL_regoffs[paren].start,
                          (IV)(PL_reg_start_tmp[paren] - PL_bostr),
-                         (IV)PL_regendp[paren],
+                         (IV)PL_regoffs[paren].end,
                          (paren > *PL_reglastparen ? "(no)" : ""));
        );
     }
-    DEBUG_EXECUTE_r(
+    DEBUG_BUFFERS_r(
        if (*PL_reglastparen + 1 <= rex->nparens) {
            PerlIO_printf(Perl_debug_log,
                          "     restoring \\%"IVdf"..\\%"IVdf" to undef\n",
@@ -289,8 +290,8 @@ S_regcppop(pTHX_ const regexp *rex)
      * --jhi */
     for (i = *PL_reglastparen + 1; i <= rex->nparens; i++) {
        if (i > PL_regsize)
-           PL_regstartp[i] = -1;
-       PL_regendp[i] = -1;
+           PL_regoffs[i].start = -1;
+       PL_regoffs[i].end = -1;
     }
 #endif
     return input;
@@ -307,7 +308,7 @@ S_regcppop(pTHX_ const regexp *rex)
  - pregexec - match a regexp against a string
  */
 I32
-Perl_pregexec(pTHX_ register regexp *prog, char *stringarg, register char *strend,
+Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, register char *strend,
         char *strbeg, I32 minend, SV *screamer, U32 nosave)
 /* strend: pointer to null at end of string */
 /* strbeg: real beginning of string */
@@ -371,7 +372,7 @@ Perl_pregexec(pTHX_ register regexp *prog, char *stringarg, register char *stren
    deleted from the finite automaton. */
 
 char *
-Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
+Perl_re_intuit_start(pTHX_ REGEXP * const prog, SV *sv, char *strpos,
                     char *strend, U32 flags, re_scream_pos_data *data)
 {
     dVAR;
@@ -1109,6 +1110,15 @@ REXEC_FBC_SCAN(                                       \
 if ((!reginfo || regtry(reginfo, &s))) \
     goto got_it
 
+#define REXEC_FBC_CSCAN(CoNdUtF8,CoNd)                         \
+    if (do_utf8) {                                             \
+       REXEC_FBC_UTF8_CLASS_SCAN(CoNdUtF8);                   \
+    }                                                          \
+    else {                                                     \
+       REXEC_FBC_CLASS_SCAN(CoNd);                            \
+    }                                                          \
+    break
+    
 #define REXEC_FBC_CSCAN_PRELOAD(UtFpReLoAd,CoNdUtF8,CoNd)      \
     if (do_utf8) {                                             \
        UtFpReLoAd;                                            \
@@ -1424,6 +1434,31 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
                !isDIGIT_LC_utf8((U8*)s),
                !isDIGIT_LC(*s)
            );
+       case LNBREAK:
+           REXEC_FBC_CSCAN(
+               is_LNBREAK_utf8(s),
+               is_LNBREAK_latin1(s)
+           );
+       case VERTWS:
+           REXEC_FBC_CSCAN(
+               is_VERTWS_utf8(s),
+               is_VERTWS_latin1(s)
+           );
+       case NVERTWS:
+           REXEC_FBC_CSCAN(
+               !is_VERTWS_utf8(s),
+               !is_VERTWS_latin1(s)
+           );
+       case HORIZWS:
+           REXEC_FBC_CSCAN(
+               is_HORIZWS_utf8(s),
+               is_HORIZWS_latin1(s)
+           );
+       case NHORIZWS:
+           REXEC_FBC_CSCAN(
+               !is_HORIZWS_utf8(s),
+               !is_HORIZWS_latin1(s)
+           );      
        case AHOCORASICKC:
        case AHOCORASICK: 
            {
@@ -1646,11 +1681,31 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
        return s;
 }
 
+static void 
+S_swap_match_buff (pTHX_ regexp *prog) {
+    regexp_paren_pair *t;
+
+    if (!prog->swap) {
+    /* We have to be careful. If the previous successful match
+       was from this regex we don't want a subsequent paritally
+       successful match to clobber the old results. 
+       So when we detect this possibility we add a swap buffer
+       to the re, and switch the buffer each match. If we fail
+       we switch it back, otherwise we leave it swapped.
+    */
+        Newxz(prog->swap, (prog->nparens + 1), regexp_paren_pair);
+    }
+    t = prog->swap;
+    prog->swap = prog->offs;
+    prog->offs = t;
+}    
+
+
 /*
  - regexec_flags - match a regexp against a string
  */
 I32
-Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *strend,
+Perl_regexec_flags(pTHX_ REGEXP * const prog, char *stringarg, register char *strend,
              char *strbeg, I32 minend, SV *sv, void *data, U32 flags)
 /* strend: pointer to null at end of string */
 /* strbeg: real beginning of string */
@@ -1669,11 +1724,11 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
     I32 end_shift = 0;                 /* Same for the end. */         /* CC */
     I32 scream_pos = -1;               /* Internal iterator of scream. */
     char *scream_olds = NULL;
-    SV* const oreplsv = GvSV(PL_replgv);
     const bool do_utf8 = (bool)DO_UTF8(sv);
     I32 multiline;
     RXi_GET_DECL(prog,progi);
     regmatch_info reginfo;  /* create some info to pass to regtry etc */
+    bool swap_on_fail = 0;
 
     GET_RE_DEBUG_FLAGS_DECL;
 
@@ -1751,26 +1806,9 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
            reginfo.ganch = strbeg;
     }
     if (PL_curpm && (PM_GETRE(PL_curpm) == prog)) {
-        I32 *t;
-        if (!progi->swap) {
-        /* We have to be careful. If the previous successful match
-           was from this regex we don't want a subsequent paritally
-           successful match to clobber the old results. 
-           So when we detect this possibility we add a swap buffer
-           to the re, and switch the buffer each match. If we fail
-           we switch it back, otherwise we leave it swapped.
-        */
-            Newxz(progi->swap, 1, regexp_paren_ofs);
-            /* no need to copy these */
-            Newxz(progi->swap->startp, prog->nparens + 1, I32);
-            Newxz(progi->swap->endp, prog->nparens + 1, I32);
-        }
-        t = progi->swap->startp;
-        progi->swap->startp = prog->startp;
-        prog->startp = t;
-        t = progi->swap->endp;
-        progi->swap->endp = prog->endp;
-        prog->endp = t;
+        swap_on_fail = 1;
+        swap_match_buff(prog); /* do we need a save destructor here for
+                                  eval dies? */
     }
     if (!(flags & REXEC_CHECKED) && (prog->check_substr != NULL || prog->check_utf8 != NULL)) {
        re_scream_pos_data d;
@@ -1983,7 +2021,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
            SV * const prop = sv_newmortal();
            regprop(prog, prop, c);
            {
-               RE_PV_QUOTED_DECL(quoted,UTF,PERL_DEBUG_PAD_ZERO(1),
+               RE_PV_QUOTED_DECL(quoted,do_utf8,PERL_DEBUG_PAD_ZERO(1),
                    s,strend-s,60);
                PerlIO_printf(Perl_debug_log,
                    "Matching stclass %.*s against %s (%d chars)\n",
@@ -2071,14 +2109,8 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
 got_it:
     RX_MATCH_TAINTED_set(prog, PL_reg_flags & RF_tainted);
 
-    if (PL_reg_eval_set) {
-       /* Preserve the current value of $^R */
-       if (oreplsv != GvSV(PL_replgv))
-           sv_setsv(oreplsv, GvSV(PL_replgv));/* So that when GvSV(replgv) is
-                                                 restored, the value remains
-                                                 the same. */
+    if (PL_reg_eval_set)
        restore_pos(aTHX_ prog);
-    }
     if (prog->paren_names) 
         (void)hv_iterinit(prog->paren_names);
 
@@ -2120,22 +2152,14 @@ phooey:
                          PL_colors[4], PL_colors[5]));
     if (PL_reg_eval_set)
        restore_pos(aTHX_ prog);
-    if (progi->swap) {
+    if (swap_on_fail) 
         /* we failed :-( roll it back */
-        I32 *t;
-        t = progi->swap->startp;
-        progi->swap->startp = prog->startp;
-        prog->startp = t;
-        t = progi->swap->endp;
-        progi->swap->endp = prog->endp;
-        prog->endp = t;
-    }
+        swap_match_buff(prog);
+    
     return 0;
 }
 
 
-
-
 /*
  - regtry - try match at specific point
  */
@@ -2143,8 +2167,6 @@ STATIC I32                        /* 0 failure, 1 success */
 S_regtry(pTHX_ regmatch_info *reginfo, char **startpos)
 {
     dVAR;
-    register I32 *sp;
-    register I32 *ep;
     CHECKPOINT lastcp;
     regexp *prog = reginfo->prog;
     RXi_GET_DECL(prog,progi);
@@ -2222,15 +2244,14 @@ S_regtry(pTHX_ regmatch_info *reginfo, char **startpos)
        prog->sublen = PL_regeol - PL_bostr; /* strend may have been modified */
     }
     DEBUG_EXECUTE_r(PL_reg_starttry = *startpos);
-    prog->startp[0] = *startpos - PL_bostr;
+    prog->offs[0].start = *startpos - PL_bostr;
     PL_reginput = *startpos;
     PL_reglastparen = &prog->lastparen;
     PL_reglastcloseparen = &prog->lastcloseparen;
     prog->lastparen = 0;
     prog->lastcloseparen = 0;
     PL_regsize = 0;
-    PL_regstartp = prog->startp;
-    PL_regendp = prog->endp;
+    PL_regoffs = prog->offs;
     if (PL_reg_start_tmpl <= prog->nparens) {
        PL_reg_start_tmpl = prog->nparens*3/2 + 3;
         if(PL_reg_start_tmp)
@@ -2254,19 +2275,19 @@ S_regtry(pTHX_ regmatch_info *reginfo, char **startpos)
      * on those tests seems to be returning null fields from matches.
      * --jhi */
 #if 1
-    sp = PL_regstartp;
-    ep = PL_regendp;
     if (prog->nparens) {
+       regexp_paren_pair *pp = PL_regoffs;
        register I32 i;
        for (i = prog->nparens; i > (I32)*PL_reglastparen; i--) {
-           *++sp = -1;
-           *++ep = -1;
+           ++pp;
+           pp->start = -1;
+           pp->end = -1;
        }
     }
 #endif
     REGCP_SET(lastcp);
     if (regmatch(reginfo, progi->program + 1)) {
-       PL_regendp[0] = PL_reginput - PL_bostr;
+       PL_regoffs[0].end = PL_reginput - PL_bostr;
        return 1;
     }
     if (reginfo->cutpoint)
@@ -2308,7 +2329,7 @@ S_regtry(pTHX_ regmatch_info *reginfo, char **startpos)
 STATIC regmatch_state *
 S_push_slab(pTHX)
 {
-#if PERL_VERSION < 9
+#if PERL_VERSION < 9 && !defined(PERL_CORE)
     dMY_CXT;
 #endif
     regmatch_slab *s = PL_regmatch_slab->next;
@@ -2479,7 +2500,7 @@ regmatch(), slabs allocated since entry are freed.
        PerlIO_printf(Perl_debug_log,                       \
            "    %*s"pp" %s%s%s%s%s\n",                     \
            depth*2, "",                                    \
-           reg_name[st->resume_state],                     \
+           PL_reg_name[st->resume_state],                     \
            ((st==yes_state||st==mark_state) ? "[" : ""),   \
            ((st==yes_state) ? "Y" : ""),                   \
            ((st==mark_state) ? "M" : ""),                  \
@@ -2597,7 +2618,7 @@ S_reg_check_named_buff_matched(pTHX_ const regexp *rex, const regnode *scan) {
     I32 *nums=(I32*)SvPVX(sv_dat);
     for ( n=0; n<SvIVX(sv_dat); n++ ) {
         if ((I32)*PL_reglastparen >= nums[n] &&
-            PL_regendp[nums[n]] != -1)
+            PL_regoffs[nums[n]].end != -1)
         {
             return nums[n];
         }
@@ -2605,10 +2626,34 @@ S_reg_check_named_buff_matched(pTHX_ const regexp *rex, const regnode *scan) {
     return 0;
 }
 
+
+/* free all slabs above current one  - called during LEAVE_SCOPE */
+
+STATIC void
+S_clear_backtrack_stack(pTHX_ void *p)
+{
+    regmatch_slab *s = PL_regmatch_slab->next;
+    PERL_UNUSED_ARG(p);
+
+    if (!s)
+       return;
+    PL_regmatch_slab->next = NULL;
+    while (s) {
+       regmatch_slab * const osl = s;
+       s = s->next;
+       Safefree(osl);
+    }
+}
+
+
+#define SETREX(Re1,Re2) \
+    if (PL_reg_eval_set) PM_SETRE((PL_reg_curpm), (Re2)); \
+    Re1 = (Re2)
+
 STATIC I32                     /* 0 failure, 1 success */
 S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
 {
-#if PERL_VERSION < 9
+#if PERL_VERSION < 9 && !defined(PERL_CORE)
     dMY_CXT;
 #endif
     dVAR;
@@ -2618,8 +2663,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
     regexp *rex = reginfo->prog;
     RXi_GET_DECL(rex,rexi);
     
-    regmatch_slab  *orig_slab;
-    regmatch_state *orig_state;
+    I32        oldsave;
 
     /* the current state. This is a cached copy of PL_regmatch_state */
     register regmatch_state *st;
@@ -2634,7 +2678,11 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
 
     bool result = 0;       /* return value of S_regmatch */
     int depth = 0;         /* depth of backtrack stack */
-    int nochange_depth = 0; /* depth of GOSUB recursion with nochange*/
+    U32 nochange_depth = 0; /* depth of GOSUB recursion with nochange */
+    const U32 max_nochange_depth =
+        (3 * rex->nparens > MAX_RECURSE_EVAL_NOCHANGE_DEPTH) ?
+        3 * rex->nparens : MAX_RECURSE_EVAL_NOCHANGE_DEPTH;
+            
     regmatch_state *yes_state = NULL; /* state to pop to on success of
                                                            subpattern */
     /* mark_state piggy backs on the yes_state logic so that when we unwind 
@@ -2653,6 +2701,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                                during a successfull match */
     U32 lastopen = 0;       /* last open we saw */
     bool has_cutgroup = RX_HAS_CUTGROUP(rex) ? 1 : 0;   
+
+    SV* const oreplsv = GvSV(PL_replgv);
                
     
     /* these three flags are set by various ops to signal information to
@@ -2674,9 +2724,9 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
     GET_RE_DEBUG_FLAGS_DECL;
 #endif
 
-    DEBUG_OPTIMISE_r( {    
+    DEBUG_OPTIMISE_r( DEBUG_EXECUTE_r({
            PerlIO_printf(Perl_debug_log,"regmatch start\n");
-    });
+    }));
     /* on first ever call to regmatch, allocate first slab */
     if (!PL_regmatch_slab) {
        Newx(PL_regmatch_slab, 1, regmatch_slab);
@@ -2685,10 +2735,10 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
        PL_regmatch_state = SLAB_FIRST(PL_regmatch_slab);
     }
 
-    /* remember current high-water mark for exit */
-    /* XXX this should be done with SAVE* instead */
-    orig_slab  = PL_regmatch_slab;
-    orig_state = PL_regmatch_state;
+    oldsave = PL_savestack_ix;
+    SAVEDESTRUCTOR_X(S_clear_backtrack_stack, NULL);
+    SAVEVPTR(PL_regmatch_slab);
+    SAVEVPTR(PL_regmatch_state);
 
     /* grab next free state slot */
     st = ++PL_regmatch_state;
@@ -2746,14 +2796,14 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
 
        case KEEPS:
            /* update the startpoint */
-           st->u.keeper.val = PL_regstartp[0];
+           st->u.keeper.val = PL_regoffs[0].start;
            PL_reginput = locinput;
-           PL_regstartp[0] = locinput - PL_bostr;
+           PL_regoffs[0].start = locinput - PL_bostr;
            PUSH_STATE_GOTO(KEEPS_next, next);
            /*NOT-REACHED*/
        case KEEPS_next_fail:
            /* rollback the start point change */
-           PL_regstartp[0] = st->u.keeper.val;
+           PL_regoffs[0].start = st->u.keeper.val;
            sayNO_SILENT;
            /*NOT-REACHED*/
        case EOL:
@@ -2869,7 +2919,6 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                ST.B = next;
                ST.jump = trie->jump;
                ST.me = scan;
-                
                /*
                   traverse the TRIE keeping track of all accepting states
                   we transition through until we get to a failing node.
@@ -2967,13 +3016,25 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                        PL_colors[4], (IV)ST.accepted, PL_colors[5] );
                );
            }}
-
-           /* FALL THROUGH */
+            goto trie_first_try; /* jump into the fail handler */
+           /* NOTREACHED */
        case TRIE_next_fail: /* we failed - try next alterative */
+            if ( ST.jump) {
+                REGCP_UNWIND(ST.cp);
+               for (n = *PL_reglastparen; n > ST.lastparen; n--)
+                   PL_regoffs[n].end = -1;
+               *PL_reglastparen = n;
+           }
+          trie_first_try:
             if (do_cutgroup) {
                 do_cutgroup = 0;
                 no_final = 0;
             }
+
+            if ( ST.jump) {
+                ST.lastparen = *PL_reglastparen;
+               REGCP_SET(ST.cp);
+            }          
            if ( ST.accepted == 1 ) {
                /* only one choice left - just continue */
                DEBUG_EXECUTE_r({
@@ -3014,8 +3075,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                
                continue; /* execute rest of RE */
            }
-
-           if (!ST.accepted-- ) {
+           
+           if ( !ST.accepted-- ) {
                DEBUG_EXECUTE_r({
                    PerlIO_printf( Perl_debug_log,
                        "%*s  %sTRIE failed...%s\n",
@@ -3026,7 +3087,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                FREETMPS;
                LEAVE;
                sayNO_SILENT;
-           }
+               /*NOTREACHED*/
+           } 
 
            /*
               There are at least two accepting states left.  Presumably
@@ -3179,8 +3241,9 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                      * pack("U0U*", 0xDF) =~ /ss/i,
                      * the 0xC3 0x9F are the UTF-8
                      * byte sequence for the U+00DF. */
+
                     if (!(do_utf8 &&
-                          toLOWER(s[0]) == 's' &&
+                          toLOWER(s[0]) == 's' &&
                           ln >= 2 &&
                           toLOWER(s[1]) == 's' &&
                           (U8)l[0] == 0xC3 &&
@@ -3475,17 +3538,17 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
            n = ARG(scan);  /* which paren pair */
            type = OP(scan);
          do_ref:  
-           ln = PL_regstartp[n];
+           ln = PL_regoffs[n].start;
            PL_reg_leftiter = PL_reg_maxiter;           /* Void cache */
            if (*PL_reglastparen < n || ln == -1)
                sayNO;                  /* Do not match unless seen CLOSEn. */
-           if (ln == PL_regendp[n])
+           if (ln == PL_regoffs[n].end)
                break;
 
            s = PL_bostr + ln;
            if (do_utf8 && type != REF) {       /* REF can do byte comparison */
                char *l = locinput;
-               const char *e = PL_bostr + PL_regendp[n];
+               const char *e = PL_bostr + PL_regoffs[n].end;
                /*
                 * Note that we can't do the "other character" lookup trick as
                 * in the 8-bit case (no pun intended) because in Unicode we
@@ -3518,7 +3581,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                 (UCHARAT(s) != (type == REFF
                                  ? PL_fold : PL_fold_locale)[nextchr])))
                sayNO;
-           ln = PL_regendp[n] - ln;
+           ln = PL_regoffs[n].end - ln;
            if (locinput + ln > PL_regeol)
                sayNO;
            if (ln > 1 && (type == REF
@@ -3546,11 +3609,11 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
             regnode *startpoint;
 
        case GOSTART:
-       case GOSUB: /*    /(...(?1))/      */
-            if (cur_eval && cur_eval->locinput==locinput) {
+       case GOSUB: /*    /(...(?1))/   /(...(?&foo))/   */
+           if (cur_eval && cur_eval->locinput==locinput) {
                 if (cur_eval->u.eval.close_paren == (U32)ARG(scan)) 
                     Perl_croak(aTHX_ "Infinite recursion in regex");
-                if ( ++nochange_depth > MAX_RECURSE_EVAL_NOCHANGE_DEPTH ) 
+                if ( ++nochange_depth > max_nochange_depth )
                     Perl_croak(aTHX_ 
                         "Pattern subroutine nesting without pos change"
                         " exceeded limit in regex");
@@ -3571,14 +3634,11 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
             /* NOTREACHED */
         case EVAL:  /*   /(?{A})B/   /(??{A})B/  and /(?(?{A})X|Y)B/   */        
             if (cur_eval && cur_eval->locinput==locinput) {
-                if ( ++nochange_depth > MAX_RECURSE_EVAL_NOCHANGE_DEPTH ) 
+               if ( ++nochange_depth > max_nochange_depth )
                     Perl_croak(aTHX_ "EVAL without pos change exceeded limit in regex");
             } else {
                 nochange_depth = 0;
             }    
-            {   regexp *ocurpm = PM_GETRE(PL_curpm);
-               char *osubbeg = rex->subbeg;
-               STRLEN osublen = rex->sublen;
            {
                /* execute the code in the {...} */
                dSP;
@@ -3586,23 +3646,18 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                OP_4tree * const oop = PL_op;
                COP * const ocurcop = PL_curcop;
                PAD *old_comppad;
-
            
                n = ARG(scan);
                PL_op = (OP_4tree*)rexi->data->data[n];
                DEBUG_STATE_r( PerlIO_printf(Perl_debug_log, 
                    "  re_eval 0x%"UVxf"\n", PTR2UV(PL_op)) );
                PAD_SAVE_LOCAL(old_comppad, (PAD*)rexi->data->data[n + 2]);
-               PL_regendp[0] = PL_reg_magic->mg_len = locinput - PL_bostr;
+               PL_regoffs[0].end = PL_reg_magic->mg_len = locinput - PL_bostr;
 
                 if (sv_yes_mark) {
                     SV *sv_mrk = get_sv("REGMARK", 1);
                     sv_setsv(sv_mrk, sv_yes_mark);
                 }
-                /* make sure that $1 and friends are available with nested eval */
-                PM_SETRE(PL_curpm,rex);
-                rex->subbeg = ocurpm->subbeg;
-                rex->sublen = ocurpm->sublen;
 
                CALLRUNOPS(aTHX);                       /* Scalar context. */
                SPAGAIN;
@@ -3616,7 +3671,6 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                PL_op = oop;
                PAD_RESTORE_LOCAL(old_comppad);
                PL_curcop = ocurcop;
-
                if (!logical) {
                    /* /(?{...})/ */
                    sv_setsv(save_scalar(PL_replgv), ret);
@@ -3641,18 +3695,14 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                    }
 
                    if (mg) {
-                       re = (regexp *)mg->mg_obj;
-                       (void)ReREFCNT_inc(re);
+                       re = reg_temp_copy((regexp *)mg->mg_obj); /*XXX:dmq*/
                    }
                    else {
-                       STRLEN len;
-                       const char * const t = SvPV_const(ret, len);
-                       PMOP pm;
+                       U32 pm_flags = 0;
                        const I32 osize = PL_regsize;
 
-                       Zero(&pm, 1, PMOP);
-                       if (DO_UTF8(ret)) pm.op_pmdynflags |= PMdf_DYN_UTF8;
-                       re = CALLREGCOMP((char*)t, (char*)t + len, &pm);
+                       if (DO_UTF8(ret)) pm_flags |= RXf_UTF8;
+                       re = CALLREGCOMP(ret, pm_flags);
                        if (!(SvFLAGS(ret)
                              & (SVs_TEMP | SVs_PADTMP | SVf_READONLY
                                | SVs_GMG)))
@@ -3661,13 +3711,10 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                        PL_regsize = osize;
                    }
                }
+                RX_MATCH_COPIED_off(re);
+                re->subbeg = rex->subbeg;
+                re->sublen = rex->sublen;
                rei = RXi_GET(re);
-
-                /* restore PL_curpm after the eval */
-                PM_SETRE(PL_curpm,ocurpm);
-                rex->sublen = osublen;
-                rex->subbeg = osubbeg;
-
                 DEBUG_EXECUTE_r(
                     debug_start_match(re, do_utf8, locinput, PL_regeol, 
                         "Matching embedded");
@@ -3681,16 +3728,14 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                         Renew(PL_reg_start_tmp, PL_reg_start_tmpl, char*);
                     else
                         Newx(PL_reg_start_tmp, PL_reg_start_tmpl, char*);
-                }
-
+                }                      
 
         eval_recurse_doit: /* Share code with GOSUB below this line */                         
                /* run the pattern returned from (??{...}) */
                ST.cp = regcppush(0);   /* Save *all* the positions. */
                REGCP_SET(ST.lastcp);
                
-               PL_regstartp = re->startp; /* essentially NOOP on GOSUB */
-               PL_regendp = re->endp;     /* essentially NOOP on GOSUB */
+               PL_regoffs = re->offs; /* essentially NOOP on GOSUB */
                
                *PL_reglastparen = 0;
                *PL_reglastcloseparen = 0;
@@ -3709,7 +3754,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
 
                ST.prev_rex = rex;
                ST.prev_curlyx = cur_curlyx;
-               rex = re;
+               SETREX(rex,re);
                rexi = rei;
                cur_curlyx = NULL;
                ST.B = next;
@@ -3719,11 +3764,6 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                PUSH_YES_STATE_GOTO(EVAL_AB, startpoint);
                /* NOTREACHED */
            }
-           /* restore PL_curpm after the eval */
-           PM_SETRE(PL_curpm,ocurpm);
-            rex->sublen = osublen;
-            rex->subbeg = osubbeg;
-           }
            /* logical is 1,   /(?(?{...})X|Y)/ */
            sw = (bool)SvTRUE(ret);
            logical = 0;
@@ -3734,13 +3774,15 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
            /* note: this is called twice; first after popping B, then A */
            PL_reg_flags ^= ST.toggle_reg_flags; 
            ReREFCNT_dec(rex);
-           rex = ST.prev_rex;
+           SETREX(rex,ST.prev_rex);
            rexi = RXi_GET(rex);
            regcpblow(ST.cp);
            cur_eval = ST.prev_eval;
            cur_curlyx = ST.prev_curlyx;
            /* XXXX This is too dramatic a measure... */
            PL_reg_maxiter = 0;
+            if ( nochange_depth )
+               nochange_depth--;
            sayYES;
 
 
@@ -3748,7 +3790,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
            /* note: this is called twice; first after popping B, then A */
            PL_reg_flags ^= ST.toggle_reg_flags; 
            ReREFCNT_dec(rex);
-           rex = ST.prev_rex;
+           SETREX(rex,ST.prev_rex);
            rexi = RXi_GET(rex); 
            PL_reginput = locinput;
            REGCP_UNWIND(ST.lastcp);
@@ -3757,6 +3799,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
            cur_curlyx = ST.prev_curlyx;
            /* XXXX This is too dramatic a measure... */
            PL_reg_maxiter = 0;
+           if ( nochange_depth )
+               nochange_depth--;
            sayNO_SILENT;
 #undef ST
 
@@ -3769,8 +3813,8 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
            break;
        case CLOSE:
            n = ARG(scan);  /* which paren pair */
-           PL_regstartp[n] = PL_reg_start_tmp[n] - PL_bostr;
-           PL_regendp[n] = locinput - PL_bostr;
+           PL_regoffs[n].start = PL_reg_start_tmp[n] - PL_bostr;
+           PL_regoffs[n].end = locinput - PL_bostr;
            /*if (n > PL_regsize)
                PL_regsize = n;*/
            if (n > *PL_reglastparen)
@@ -3790,8 +3834,9 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                     if ( OP(cursor)==CLOSE ){
                         n = ARG(cursor);
                         if ( n <= lastopen ) {
-                            PL_regstartp[n] = PL_reg_start_tmp[n] - PL_bostr;
-                            PL_regendp[n] = locinput - PL_bostr;
+                            PL_regoffs[n].start
+                               = PL_reg_start_tmp[n] - PL_bostr;
+                            PL_regoffs[n].end = locinput - PL_bostr;
                             /*if (n > PL_regsize)
                             PL_regsize = n;*/
                             if (n > *PL_reglastparen)
@@ -3808,7 +3853,7 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
            /*NOTREACHED*/          
        case GROUPP:
            n = ARG(scan);  /* which paren pair */
-           sw = (bool)(*PL_reglastparen >= n && PL_regendp[n] != -1);
+           sw = (bool)(*PL_reglastparen >= n && PL_regoffs[n].end != -1);
            break;
        case NGROUPP:
            /* reg_check_named_buff_matched returns 0 for no match */
@@ -3956,15 +4001,6 @@ NULL
        }
 
        case CURLYX_end: /* just finished matching all of A*B */
-           if (PL_reg_eval_set){
-               SV *pres= GvSV(PL_replgv);
-               SvREFCNT_inc(pres);
-               regcpblow(ST.cp);
-               sv_setsv(GvSV(PL_replgv), pres);
-               SvREFCNT_dec(pres);
-           } else {
-               regcpblow(ST.cp);
-           }
            cur_curlyx = ST.prev_curlyx;
            sayYES;
            /* NOTREACHED */
@@ -4226,7 +4262,7 @@ NULL
            }
            REGCP_UNWIND(ST.cp);
            for (n = *PL_reglastparen; n > ST.lastparen; n--)
-               PL_regendp[n] = -1;
+               PL_regoffs[n].end = -1;
            *PL_reglastparen = n;
            /*dmq: *PL_reglastcloseparen = n; */
            scan = ST.next_branch;
@@ -4377,6 +4413,12 @@ NULL
                    && UCHARAT(PL_reginput) != ST.c2)
            {
                /* simulate B failing */
+               DEBUG_OPTIMISE_r(
+                   PerlIO_printf(Perl_debug_log,
+                       "%*s  CURLYM Fast bail c1=%"IVdf" c2=%"IVdf"\n",
+                       (int)(REPORT_CODE_OFF+(depth*2)),"",
+                       (IV)ST.c1,(IV)ST.c2
+               ));
                state_num = CURLYM_B_fail;
                goto reenter_switch;
            }
@@ -4385,13 +4427,13 @@ NULL
                /* mark current A as captured */
                I32 paren = ST.me->flags;
                if (ST.count) {
-                   PL_regstartp[paren]
+                   PL_regoffs[paren].start
                        = HOPc(PL_reginput, -ST.alen) - PL_bostr;
-                   PL_regendp[paren] = PL_reginput - PL_bostr;
+                   PL_regoffs[paren].end = PL_reginput - PL_bostr;
                    /*dmq: *PL_reglastcloseparen = paren; */
                }
                else
-                   PL_regendp[paren] = -1;
+                   PL_regoffs[paren].end = -1;
                if (cur_eval && cur_eval->u.eval.close_paren &&
                    cur_eval->u.eval.close_paren == (U32)ST.me->flags) 
                {
@@ -4425,12 +4467,12 @@ NULL
 #define CURLY_SETPAREN(paren, success) \
     if (paren) { \
        if (success) { \
-           PL_regstartp[paren] = HOPc(locinput, -1) - PL_bostr; \
-           PL_regendp[paren] = locinput - PL_bostr; \
+           PL_regoffs[paren].start = HOPc(locinput, -1) - PL_bostr; \
+           PL_regoffs[paren].end = locinput - PL_bostr; \
            *PL_reglastcloseparen = paren; \
        } \
        else \
-           PL_regendp[paren] = -1; \
+           PL_regoffs[paren].end = -1; \
     }
 
        case STAR:              /*  /A*B/ where A is width 1 */
@@ -4603,7 +4645,7 @@ NULL
        case CURLY_B_min_known_fail:
            /* failed to find B in a non-greedy match where c1,c2 valid */
            if (ST.paren && ST.count)
-               PL_regendp[ST.paren] = -1;
+               PL_regoffs[ST.paren].end = -1;
 
            PL_reginput = locinput;     /* Could be reset... */
            REGCP_UNWIND(ST.cp);
@@ -4681,7 +4723,7 @@ NULL
        case CURLY_B_min_fail:
            /* failed to find B in a non-greedy match where c1,c2 invalid */
            if (ST.paren && ST.count)
-               PL_regendp[ST.paren] = -1;
+               PL_regoffs[ST.paren].end = -1;
 
            REGCP_UNWIND(ST.cp);
            /* failed -- move forward one */
@@ -4728,7 +4770,7 @@ NULL
        case CURLY_B_max_fail:
            /* failed to find B in a greedy match */
            if (ST.paren && ST.count)
-               PL_regendp[ST.paren] = -1;
+               PL_regoffs[ST.paren].end = -1;
 
            REGCP_UNWIND(ST.cp);
            /*  back up. */
@@ -4744,14 +4786,12 @@ NULL
            if (cur_eval) {
                /* we've just finished A in /(??{A})B/; now continue with B */
                I32 tmpix;
-
-
                st->u.eval.toggle_reg_flags
                            = cur_eval->u.eval.toggle_reg_flags;
                PL_reg_flags ^= st->u.eval.toggle_reg_flags; 
 
                st->u.eval.prev_rex = rex;              /* inner */
-               rex  = cur_eval->u.eval.prev_rex;       /* outer */
+               SETREX(rex,cur_eval->u.eval.prev_rex);
                rexi = RXi_GET(rex);
                cur_curlyx = cur_eval->u.eval.prev_curlyx;
                ReREFCNT_inc(rex);
@@ -4771,7 +4811,10 @@ NULL
                DEBUG_EXECUTE_r(
                    PerlIO_printf(Perl_debug_log, "%*s  EVAL trying tail ... %"UVxf"\n",
                                      REPORT_CODE_OFF+depth*2, "",PTR2UV(cur_eval)););
-               PUSH_YES_STATE_GOTO(EVAL_AB,
+                if ( nochange_depth )
+                   nochange_depth--;
+
+                PUSH_YES_STATE_GOTO(EVAL_AB,
                        st->u.eval.prev_eval->u.eval.B); /* match B */
            }
 
@@ -4961,6 +5004,55 @@ NULL
             sayNO;
             /* NOTREACHED */
 #undef ST
+        case FOLDCHAR:
+            n = ARG(scan);
+            if ( n == what_len_TRICKYFOLD(locinput,do_utf8,ln) ) {
+                locinput += ln;
+            } else if ( 0xDF == n && !do_utf8 && !UTF ) {
+                sayNO;
+            } else  {
+                U8 folded[UTF8_MAXBYTES_CASE+1];
+                STRLEN foldlen;
+                const char * const l = locinput;
+                char *e = PL_regeol;
+                to_uni_fold(n, folded, &foldlen);
+
+               if (ibcmp_utf8((const char*) folded, 0,  foldlen, 1,
+                              l, &e, 0,  do_utf8)) {
+                        sayNO;
+                }
+                locinput = e;
+            } 
+            nextchr = UCHARAT(locinput);  
+            break;
+        case LNBREAK:
+            if ((n=is_LNBREAK(locinput,do_utf8))) {
+                locinput += n;
+                nextchr = UCHARAT(locinput);
+            } else
+                sayNO;
+            break;
+
+#define CASE_CLASS(nAmE)                              \
+        case nAmE:                                    \
+            if ((n=is_##nAmE(locinput,do_utf8))) {    \
+                locinput += n;                        \
+                nextchr = UCHARAT(locinput);          \
+            } else                                    \
+                sayNO;                                \
+            break;                                    \
+        case N##nAmE:                                 \
+            if ((n=is_##nAmE(locinput,do_utf8))) {    \
+                sayNO;                                \
+            } else {                                  \
+                locinput += UTF8SKIP(locinput);       \
+                nextchr = UCHARAT(locinput);          \
+            }                                         \
+            break
+
+        CASE_CLASS(VERTWS);
+        CASE_CLASS(HORIZWS);
+#undef CASE_CLASS
 
        default:
            PerlIO_printf(Perl_error_log, "%"UVxf" %d\n",
@@ -4996,7 +5088,7 @@ NULL
                     }
                     PerlIO_printf(Perl_error_log, "%*s#%-3d %-10s %s\n",
                         REPORT_CODE_OFF + 2 + depth * 2,"",
-                        curd, reg_name[cur->resume_state],
+                        curd, PL_reg_name[cur->resume_state],
                         (curyes == cur) ? "yes" : ""
                     );
                     if (curyes == cur)
@@ -5075,6 +5167,15 @@ yes:
     DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%sMatch successful!%s\n",
                          PL_colors[4], PL_colors[5]));
 
+    if (PL_reg_eval_set) {
+       /* each successfully executed (?{...}) block does the equivalent of
+        *   local $^R = do {...}
+        * When popping the save stack, all these locals would be undone;
+        * bypass this by setting the outermost saved $^R to the latest
+        * value */
+       if (oreplsv != GvSV(PL_replgv))
+           sv_setsv(oreplsv, GvSV(PL_replgv));
+    }
     result = 1;
     goto final_exit;
 
@@ -5131,20 +5232,9 @@ no_silent:
         sv_setsv(sv_err, sv_commit);
         sv_setsv(sv_mrk, sv_yes_mark);
     }
-    /* restore original high-water mark */
-    PL_regmatch_slab  = orig_slab;
-    PL_regmatch_state = orig_state;
-
-    /* free all slabs above current one */
-    if (orig_slab->next) {
-       regmatch_slab *sl = orig_slab->next;
-       orig_slab->next = NULL;
-       while (sl) {
-           regmatch_slab * const osl = sl;
-           sl = sl->next;
-           Safefree(osl);
-       }
-    }
+
+    /* clean up; in particular, free all slabs above current one */
+    LEAVE_SCOPE(oldsave);
 
     return result;
 }
@@ -5166,6 +5256,9 @@ S_regrepeat(pTHX_ const regexp *prog, const regnode *p, I32 max, int depth)
     register char *loceol = PL_regeol;
     register I32 hardcount = 0;
     register bool do_utf8 = PL_reg_match_utf8;
+#ifndef DEBUGGING
+    PERL_UNUSED_ARG(depth);
+#endif
 
     scan = PL_reginput;
     if (max == REG_INFTY)
@@ -5371,7 +5464,77 @@ S_regrepeat(pTHX_ const regexp *prog, const regnode *p, I32 max, int depth)
            while (scan < loceol && !isDIGIT(*scan))
                scan++;
        }
+    case LNBREAK:
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol && (c=is_LNBREAK_utf8(scan))) {
+               scan += c;
+               hardcount++;
+           }
+       } else {
+           /*
+             LNBREAK can match two latin chars, which is ok,
+             because we have a null terminated string, but we
+             have to use hardcount in this situation
+           */
+           while (scan < loceol && (c=is_LNBREAK_latin1(scan)))  {
+               scan+=c;
+               hardcount++;
+           }
+       }       
+       break;
+    case HORIZWS:
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol && (c=is_HORIZWS_utf8(scan))) {
+               scan += c;
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && is_HORIZWS_latin1(scan)) 
+               scan++;         
+       }       
+       break;
+    case NHORIZWS:
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol && !is_HORIZWS_utf8(scan)) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && !is_HORIZWS_latin1(scan))
+               scan++;
+
+       }       
+       break;
+    case VERTWS:
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol && (c=is_VERTWS_utf8(scan))) {
+               scan += c;
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && is_VERTWS_latin1(scan)) 
+               scan++;
+
+       }       
+       break;
+    case NVERTWS:
+        if (do_utf8) {
+           loceol = PL_regeol;
+           while (hardcount < max && scan < loceol && !is_VERTWS_utf8(scan)) {
+               scan += UTF8SKIP(scan);
+               hardcount++;
+           }
+       } else {
+           while (scan < loceol && !is_VERTWS_latin1(scan)) 
+               scan++;
+          
+       }       
        break;
+
     default:           /* Called on something of 0 width. */
        break;          /* So match right here or not at all. */
     }
@@ -5690,10 +5853,18 @@ S_to_utf8_substr(pTHX_ register regexp *prog)
            SV* const sv = newSVsv(prog->substrs->data[i].substr);
            prog->substrs->data[i].utf8_substr = sv;
            sv_utf8_upgrade(sv);
-           if (SvVALID(prog->substrs->data[i].substr))
-               fbm_compile(sv, 0);
-           if (SvTAIL(prog->substrs->data[i].substr))
-               SvTAIL_on(sv);
+           if (SvVALID(prog->substrs->data[i].substr)) {
+               const U8 flags = BmFLAGS(prog->substrs->data[i].substr);
+               if (flags & FBMcf_TAIL) {
+                   /* Trim the trailing \n that fbm_compile added last
+                      time.  */
+                   SvCUR_set(sv, SvCUR(sv) - 1);
+                   /* Whilst this makes the SV technically "invalid" (as its
+                      buffer is no longer followed by "\0") when fbm_compile()
+                      adds the "\n" back, a "\0" is restored.  */
+               }
+               fbm_compile(sv, flags);
+           }
            if (prog->substrs->data[i].substr == prog->check_substr)
                prog->check_utf8 = sv;
        }
@@ -5710,10 +5881,16 @@ S_to_byte_substr(pTHX_ register regexp *prog)
            && !prog->substrs->data[i].substr) {
            SV* sv = newSVsv(prog->substrs->data[i].utf8_substr);
            if (sv_utf8_downgrade(sv, TRUE)) {
-               if (SvVALID(prog->substrs->data[i].utf8_substr))
-                   fbm_compile(sv, 0);
-               if (SvTAIL(prog->substrs->data[i].utf8_substr))
-                   SvTAIL_on(sv);
+               if (SvVALID(prog->substrs->data[i].utf8_substr)) {
+                   const U8 flags
+                       = BmFLAGS(prog->substrs->data[i].utf8_substr);
+                   if (flags & FBMcf_TAIL) {
+                       /* Trim the trailing \n that fbm_compile added last
+                          time.  */
+                       SvCUR_set(sv, SvCUR(sv) - 1);
+                   }
+                   fbm_compile(sv, flags);
+               }           
            } else {
                SvREFCNT_dec(sv);
                sv = &PL_sv_undef;