Race condition fix in threads.pm
[p5sagit/p5-mst-13.2.git] / regexec.c
index 59d5624..1a86e49 100644 (file)
--- a/regexec.c
+++ b/regexec.c
                ? (U8*)pos - off                \
                : NULL)
 
-#define HOP3(pos,off,lim) (PL_reg_match_utf8 ? reghop3((U8*)pos, off, (U8*)lim) : (U8*)(pos + off))
+#define HOP3(pos,off,lim) (PL_reg_match_utf8 ? reghop3((U8*)(pos), off, (U8*)(lim)) : (U8*)(pos + off))
 #define HOP3c(pos,off,lim) ((char*)HOP3(pos,off,lim))
 
 #define LOAD_UTF8_CHARCLASS(class,str) STMT_START { \
@@ -197,17 +197,16 @@ S_regcppush(pTHX_ I32 parenfloor)
 /* These are needed since we do not localize EVAL nodes: */
 #define REGCP_SET(cp)                                           \
     DEBUG_STATE_r(                                              \
-        if (cp != PL_savestack_ix)                             \
             PerlIO_printf(Perl_debug_log,                      \
-                            "  Setting an EVAL scope, savestack=%"IVdf"\n",    \
+               "  Setting an EVAL scope, savestack=%"IVdf"\n", \
                (IV)PL_savestack_ix));                          \
     cp = PL_savestack_ix
 
 #define REGCP_UNWIND(cp)                                        \
-    DEBUG_EXECUTE_r(                                            \
+    DEBUG_STATE_r(                                              \
         if (cp != PL_savestack_ix)                             \
-                               PerlIO_printf(Perl_debug_log,           \
-                               "  Clearing an EVAL scope, savestack=%"IVdf"..%"IVdf"\n", \
+           PerlIO_printf(Perl_debug_log,                       \
+               "  Clearing an EVAL scope, savestack=%"IVdf"..%"IVdf"\n", \
                (IV)(cp), (IV)PL_savestack_ix));                \
     regcpblow(cp)
 
@@ -357,7 +356,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
     register SV *check;
     char *strbeg;
     char *t;
-    const int do_utf8 = sv ? SvUTF8(sv) : 0;   /* if no sv we have to assume bytes */
+    const bool do_utf8 = (sv && SvUTF8(sv)) ? 1 : 0; /* if no sv we have to assume bytes */
     I32 ml_anch;
     register char *other_last = NULL;  /* other substr checked before this */
     char *check_at = NULL;             /* check substr found at this pos */
@@ -375,7 +374,8 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
     }
     DEBUG_EXECUTE_r( 
         debug_start_match(prog, do_utf8, strpos, strend, 
-            "Guessing start of match for");
+            sv ? "Guessing start of match in sv for"
+               : "Guessing start of match in string for");
              );
 
     /* CHR_DIST() would be more correct here but it makes things slow. */
@@ -384,6 +384,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                              "String too short... [re_intuit_start]\n"));
        goto fail;
     }
+                
     strbeg = (sv && SvPOK(sv)) ? strend - SvCUR(sv) : strpos;
     PL_regeol = strend;
     if (do_utf8) {
@@ -395,9 +396,9 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
            to_byte_substr(prog);
        check = prog->check_substr;
     }
-   if (check == &PL_sv_undef) {
+    if (check == &PL_sv_undef) {
        DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
-               "Non-utf string cannot match utf check string\n"));
+               "Non-utf8 string cannot match utf8 check string\n"));
        goto fail;
     }
     if (prog->reganch & ROPT_ANCH) {   /* Match at beg-of-str or after \n */
@@ -420,6 +421,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
            I32 slen;
 
            s = HOP3c(strpos, prog->check_offset_min, strend);
+           
            if (SvTAIL(check)) {
                slen = SvCUR(check);    /* >= 1 */
 
@@ -449,8 +451,8 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
        /* Match is anchored, but substr is not anchored wrt beg-of-str. */
        s = strpos;
        start_shift = prog->check_offset_min; /* okay to underestimate on CC */
-       end_shift = prog->minlen - start_shift -
-           CHR_SVLEN(check) + (SvTAIL(check) != 0);
+       end_shift = prog->check_end_shift;
+       
        if (!ml_anch) {
            const I32 end = prog->check_offset_max + CHR_SVLEN(check)
                                         - (SvTAIL(check) != 0);
@@ -463,20 +465,37 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
     else {                             /* Can match at random position */
        ml_anch = 0;
        s = strpos;
-       start_shift = prog->check_offset_min; /* okay to underestimate on CC */
-       /* Should be nonnegative! */
-       end_shift = prog->minlen - start_shift -
-           CHR_SVLEN(check) + (SvTAIL(check) != 0);
+       start_shift = prog->check_offset_min;  /* okay to underestimate on CC */
+       end_shift = prog->check_end_shift;
+       
+       /* end shift should be non negative here */
     }
 
 #ifdef DEBUGGING       /* 7/99: reports of failure (with the older version) */
     if (end_shift < 0)
-       Perl_croak(aTHX_ "panic: end_shift");
+       Perl_croak(aTHX_ "panic: end_shift: %"IVdf" pattern:\n%s\n ",
+           end_shift,prog->precomp);
 #endif
 
   restart:
     /* Find a possible match in the region s..strend by looking for
        the "check" substring in the region corrected by start/end_shift. */
+    
+    {
+        I32 srch_start_shift = start_shift;
+        I32 srch_end_shift = end_shift;
+        if (srch_start_shift < 0 && strbeg - s > srch_start_shift) {
+           srch_end_shift -= ((strbeg - s) - srch_start_shift); 
+           srch_start_shift = strbeg - s;
+       }
+    DEBUG_OPTIMISE_r({
+        PerlIO_printf(Perl_debug_log, "Check offset min: %"IVdf" Start shift: %"IVdf" End shift %"IVdf" Real End Shift: %"IVdf"\n",
+            (IV)prog->check_offset_min,
+            (IV)srch_start_shift,
+            (IV)srch_end_shift, 
+            (IV)prog->check_end_shift);
+    });       
+        
     if (flags & REXEC_SCREAM) {
        I32 p = -1;                     /* Internal iterator of scream. */
        I32 * const pp = data ? data->scream_pos : &p;
@@ -486,7 +505,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                 && (BmPREVIOUS(check) == SvCUR(check) - 1)
                 && SvTAIL(check) ))
            s = screaminstr(sv, check,
-                           start_shift + (s - strbeg), end_shift, pp, 0);
+                           srch_start_shift + (s - strbeg), srch_end_shift, pp, 0);
        else
            goto fail_finish;
        /* we may be pointing at the wrong string */
@@ -495,15 +514,27 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
        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, multiline ? FBMrf_MULTILINE : 0);
-    else
-       s = fbm_instr(HOP3(s, start_shift, strend),
-                     HOP3(strend, -end_shift, strbeg),
+    else {
+        U8* start_point;
+        U8* end_point;
+        if (prog->reganch & ROPT_CANY_SEEN) {
+            start_point= (U8*)(s + srch_start_shift);
+            end_point= (U8*)(strend - srch_end_shift);
+        } else {
+           start_point= HOP3(s, srch_start_shift, srch_start_shift < 0 ? strbeg : strend);
+            end_point= HOP3(strend, -srch_end_shift, strbeg);
+       }
+       DEBUG_OPTIMISE_r({
+            PerlIO_printf(Perl_debug_log, "fbm_instr len=%d str=<%.*s>\n", 
+                (int)(end_point - start_point),
+                (int)(end_point - start_point), 
+                start_point);
+        });
+
+       s = fbm_instr( start_point, end_point,
                      check, multiline ? FBMrf_MULTILINE : 0);
-
+    }
+    }
     /* Update the count-of-usability, remove useless subpatterns,
        unshift s.  */
 
@@ -521,12 +552,20 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
 
     if (!s)
        goto fail_finish;
-
-    check_at = s;
-
     /* Finish the diagnostic message */
     DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "%ld...\n", (long)(s - i_strpos)) );
 
+    /* XXX dmq: first branch is for positive lookbehind...
+       Our check string is offset from the beginning of the pattern.
+       So we need to do any stclass tests offset forward from that 
+       point. I think. :-(
+     */
+    
+        
+    
+    check_at=s;
+     
+
     /* Got a candidate.  Check MBOL anchoring, and the *other* substr.
        Start with the other substr.
        XXXX no SCREAM optimization yet - and a very coarse implementation
@@ -535,7 +574,9 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
        Probably it is right to do no SCREAM here...
      */
 
-    if (do_utf8 ? (prog->float_utf8 && prog->anchored_utf8) : (prog->float_substr && prog->anchored_substr)) {
+    if (do_utf8 ? (prog->float_utf8 && prog->anchored_utf8) 
+                : (prog->float_substr && prog->anchored_substr)) 
+    {
        /* Take into account the "other" substring. */
        /* XXXX May be hopelessly wrong for UTF... */
        if (!other_last)
@@ -562,12 +603,17 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
                last2 = last1 = HOP3c(strend, -prog->minlen, strbeg);
                if (last < last1)
                    last1 = last;
- /* XXXX It is not documented what units *_offsets are in.  Assume bytes.  */
+                /* XXXX It is not documented what units *_offsets are in.  
+                   We assume bytes, but this is clearly wrong. 
+                   Meaning this code needs to be carefully reviewed for errors.
+                   dmq.
+                  */
                /* On end-of-str: see comment below. */
                must = do_utf8 ? prog->anchored_utf8 : prog->anchored_substr;
                if (must == &PL_sv_undef) {
                    s = (char*)NULL;
-                   DEBUG_EXECUTE_r(must = prog->anchored_utf8);        /* for debug */
+                   DEBUG_r(must = prog->anchored_utf8);        /* for debug */
                }
                else
                    s = fbm_instr(
@@ -631,7 +677,7 @@ 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_EXECUTE_r(must = prog->float_utf8);       /* for debug message */
+               DEBUG_r(must = prog->float_utf8);       /* for debug message */
            }
            else
                s = fbm_instr((unsigned char*)s,
@@ -670,11 +716,26 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
        }
     }
 
-    t = s - prog->check_offset_max;
+    
+    t= (char*)HOP3( s, -prog->check_offset_max, (prog->check_offset_max<0) ? strend : strpos);
+        
+    DEBUG_OPTIMISE_r(
+        PerlIO_printf(Perl_debug_log, 
+            "Check offset min:%"IVdf" max:%"IVdf" S:%"IVdf" t:%"IVdf" D:%"IVdf" end:%"IVdf"\n",
+            (IV)prog->check_offset_min,
+            (IV)prog->check_offset_max,
+            (IV)(s-strpos),
+            (IV)(t-strpos),
+            (IV)(t-s),
+            (IV)(strend-strpos)
+        )
+    );
+
     if (s - strpos > prog->check_offset_max  /* signed-corrected t > strpos */
         && (!do_utf8
-           || ((t = (char*)reghopmaybe3((U8*)s, -prog->check_offset_max, (U8*)strpos))
-                && t > strpos))) {
+           || ((t = (char*)reghopmaybe3((U8*)s, -prog->check_offset_max, (U8*) ((prog->check_offset_max<0) ? strend : strpos)))
+                && t > strpos))) 
+    {
        /* Fixed substring is found far enough so that the match
           cannot start at strpos. */
       try_at_offset:
@@ -783,7 +844,9 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
 
     /* Last resort... */
     /* XXXX BmUSEFUL already changed, maybe multiple change is meaningful... */
-    if (prog->regstclass && OP(prog->regstclass)!=TRIE) {
+    /* trie stclasses are too expensive to use here, we are better off to
+       leave it to regmatch itself */
+    if (prog->regstclass && PL_regkind[OP(prog->regstclass)]!=TRIE) {
        /* minlen == 0 is possible if regstclass is \b or \B,
           and the fixed substr is ''$.
           Since minlen is already taken into account, s+1 is before strend;
@@ -796,14 +859,17 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
         const int cl_l = (PL_regkind[OP(prog->regstclass)] == EXACT
                    ? CHR_DIST(str+STR_LEN(prog->regstclass), str)
                    : 1);
-       const char * endpos = (prog->anchored_substr || prog->anchored_utf8 || ml_anch)
-               ? HOP3c(s, (prog->minlen ? cl_l : 0), strend)
-               : (prog->float_substr || prog->float_utf8
-                  ? HOP3c(HOP3c(check_at, -start_shift, strbeg),
-                          cl_l, strend)
-                  : strend);
-        /*if (OP(prog->regstclass) == TRIE)
-            endpos++;*/
+       char * endpos;
+       if (prog->anchored_substr || prog->anchored_utf8 || ml_anch)
+            endpos= HOP3c(s, (prog->minlen ? cl_l : 0), strend);
+        else if (prog->float_substr || prog->float_utf8)
+           endpos= HOP3c(HOP3c(check_at, -start_shift, strbeg), cl_l, strend);
+        else 
+            endpos= strend;
+                   
+        DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log, "start_shift: %"IVdf" check_at: %d s: %d endpos: %d\n",
+                      start_shift,check_at-strbeg,s-strbeg,endpos-strbeg));
+       
        t = s;
         s = find_byclass(prog, prog->regstclass, s, endpos, NULL);
        if (!s) {
@@ -896,10 +962,7 @@ Perl_re_intuit_start(pTHX_ regexp *prog, SV *sv, char *strpos,
     return NULL;
 }
 
-/* We know what class REx starts with.  Try to find this position... */
-/* if reginfo is NULL, its a dryrun */
-/* annoyingly all the vars in this routine have different names from their counterparts
-   in regmatch. /grrr */
+
 
 #define REXEC_TRIE_READ_CHAR(trie_type, trie, uc, uscan, len, uvc, charid,  \
 foldlen, foldbuf, uniflags) STMT_START {                                    \
@@ -1039,6 +1102,14 @@ if ((!reginfo || regtry(reginfo, s))) \
     }                                                          \
     break
 
+#define DUMP_EXEC_POS(li,s,doutf8) \
+    dump_exec_pos(li,s,(PL_regeol),(PL_bostr),(PL_reg_starttry),doutf8)
+
+/* We know what class REx starts with.  Try to find this position... */
+/* if reginfo is NULL, its a dryrun */
+/* annoyingly all the vars in this routine have different names from their counterparts
+   in regmatch. /grrr */
+
 STATIC char *
 S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s, 
     const char *strend, const regmatch_info *reginfo)
@@ -1325,8 +1396,8 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
                !isDIGIT_LC_utf8((U8*)s),
                !isDIGIT_LC(*s)
            );
-       case TRIE: 
-           /*Perl_croak(aTHX_ "panic: unknown regstclass TRIE");*/
+       case AHOCORASICKC:
+       case AHOCORASICK: 
            {
                const enum { trie_plain, trie_utf8, trie_utf8_fold }
                    trie_type = do_utf8 ?
@@ -1344,11 +1415,13 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
                STRLEN maxlen = trie->maxlen;
                SV *sv_points;
                U8 **points; /* map of where we were in the input string
-                               when reading a given string. For ASCII this
+                               when reading a given char. For ASCII this
                                is unnecessary overhead as the relationship
                                is always 1:1, but for unicode, especially
                                case folded unicode this is not true. */
                U8 foldbuf[ UTF8_MAXBYTES_CASE + 1 ];
+               U8 *bitmap=NULL;
+
 
                 GET_RE_DEBUG_FLAGS_DECL;
 
@@ -1363,13 +1436,31 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
                 SvPOK_on(sv_points);
                 sv_2mortal(sv_points);
                 points=(U8**)SvPV_nolen(sv_points );
-
-               if (trie->bitmap && trie_type != trie_utf8_fold) {
-                   while (s <= last_start && !TRIE_BITMAP_TEST(trie,*s) ) {
-                       s++;
-                   }
+                if ( trie_type != trie_utf8_fold 
+                     && (trie->bitmap || OP(c)==AHOCORASICKC) ) 
+                {
+                    if (trie->bitmap) 
+                        bitmap=(U8*)trie->bitmap;
+                    else
+                        bitmap=(U8*)ANYOF_BITMAP(c);
                 }
-
+                /* this is the Aho-Corasick algorithm modified a touch
+                   to include special handling for long "unknown char" 
+                   sequences. The basic idea being that we use AC as long
+                   as we are dealing with a possible matching char, when
+                   we encounter an unknown char (and we have not encountered
+                   an accepting state) we scan forward until we find a legal 
+                   starting char. 
+                   AC matching is basically that of trie matching, except
+                   that when we encounter a failing transition, we fall back
+                   to the current states "fail state", and try the current char 
+                   again, a process we repeat until we reach the root state, 
+                   state 1, or a legal transition. If we fail on the root state 
+                   then we can either terminate if we have reached an accepting 
+                   state previously, or restart the entire process from the beginning 
+                   if we have not.
+
+                 */
                 while (s <= last_start) {
                     const U32 uniflags = UTF8_ALLOW_DEFAULT;
                     U8 *uc = (U8*)s;
@@ -1381,39 +1472,68 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
                     STRLEN foldlen = 0;
                     U8 *uscan = (U8*)NULL;
                     U8 *leftmost = NULL;
-
+#ifdef DEBUGGING                    
+                    U32 accepted_word= 0;
+#endif
                     U32 pointpos = 0;
 
                     while ( state && uc <= (U8*)strend ) {
                         int failed=0;
-                        if (aho->states[ state ].wordnum) {
-                            U8 *lpos= points[ (pointpos - trie->wordlen[aho->states[ state ].wordnum-1] ) % maxlen ];
-                            if (!leftmost || lpos < leftmost)
+                        U32 word = aho->states[ state ].wordnum;
+
+                        if( state==1 ) {
+                            if ( bitmap ) {
+                                DEBUG_TRIE_EXECUTE_r(
+                                    if ( uc <= (U8*)last_start && !BITMAP_TEST(bitmap,*uc) ) {
+                                        dump_exec_pos( (char *)uc, c, strend, real_start, 
+                                            (char *)uc, do_utf8 );
+                                        PerlIO_printf( Perl_debug_log,
+                                            " Scanning for legal start char...\n");
+                                    }
+                                );            
+                                while ( uc <= (U8*)last_start  && !BITMAP_TEST(bitmap,*uc) ) {
+                                    uc++;
+                                }
+                                s= (char *)uc;
+                            }
+                            if (uc >(U8*)last_start) break;
+                        }
+                                            
+                        if ( word ) {
+                            U8 *lpos= points[ (pointpos - trie->wordlen[word-1] ) % maxlen ];
+                            if (!leftmost || lpos < leftmost) {
+                                DEBUG_r(accepted_word=word);
                                 leftmost= lpos;
+                            }
                             if (base==0) break;
+                            
                         }
                         points[pointpos++ % maxlen]= uc;
                        REXEC_TRIE_READ_CHAR(trie_type, trie, uc, uscan, len,
                            uvc, charid, foldlen, foldbuf, uniflags);
-                        DEBUG_TRIE_EXECUTE_r(
+                        DEBUG_TRIE_EXECUTE_r({
+                            dump_exec_pos( (char *)uc, c, strend, real_start, 
+                                s,   do_utf8 );
                             PerlIO_printf(Perl_debug_log,
-                                "Pos: %d Charid:%3x CV:%4"UVxf" ",
-                                (int)((const char*)uc - real_start), charid, uvc)
-                        );
-                        uc += len;
+                                " Charid:%3u CP:%4"UVxf" ",
+                                 charid, uvc);
+                        });
 
                         do {
 #ifdef DEBUGGING
-                            U32 word = aho->states[ state ].wordnum;
+                            word = aho->states[ state ].wordnum;
 #endif
                             base = aho->states[ state ].trans.base;
 
-                            DEBUG_TRIE_EXECUTE_r(
+                            DEBUG_TRIE_EXECUTE_r({
+                                if (failed) 
+                                    dump_exec_pos( (char *)uc, c, strend, real_start, 
+                                        s,   do_utf8 );
                                 PerlIO_printf( Perl_debug_log,
-                                    "%sState: %4"UVxf", Base: 0x%-4"UVxf" uvc=%"UVxf" word=%"UVxf"\n",
-                                    failed ? "Fail transition to " : "",
-                                    state, base, uvc, word)
-                            );
+                                    "%sState: %4"UVxf", word=%"UVxf,
+                                    failed ? " Fail transition to " : "",
+                                    (UV)state, (UV)word);
+                            });
                             if ( base ) {
                                 U32 tmp;
                                 if (charid &&
@@ -1425,53 +1545,60 @@ S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
                                      && (tmp=trie->trans[base + charid - 1 -
                                         trie->uniquecharcount ].next))
                                 {
+                                    DEBUG_TRIE_EXECUTE_r(
+                                        PerlIO_printf( Perl_debug_log," - legal\n"));
                                     state = tmp;
                                     break;
                                 }
                                 else {
-                                    failed++;
-                                    if ( state == 1 )
-                                        break;
-                                    else
-                                        state = aho->fail[state];
+                                    DEBUG_TRIE_EXECUTE_r(
+                                        PerlIO_printf( Perl_debug_log," - fail\n"));
+                                    failed = 1;
+                                    state = aho->fail[state];
                                 }
                             }
                             else {
                                 /* we must be accepting here */
-                                failed++;
+                                DEBUG_TRIE_EXECUTE_r(
+                                        PerlIO_printf( Perl_debug_log," - accepting\n"));
+                                failed = 1;
                                 break;
                             }
                         } while(state);
+                        uc += len;
                         if (failed) {
                             if (leftmost)
                                 break;
-                            else if (!charid && trie->bitmap && trie_type != trie_utf8_fold) {
-                                while ( uc <= (U8*)last_start  && !TRIE_BITMAP_TEST(trie,*uc) ) {
-                                    uc++;
-                                }
-                            }
+                            if (!state) state = 1;
                         }
                     }
                     if ( aho->states[ state ].wordnum ) {
                         U8 *lpos = points[ (pointpos - trie->wordlen[aho->states[ state ].wordnum-1]) % maxlen ];
-                        if (!leftmost || lpos < leftmost)
+                        if (!leftmost || lpos < leftmost) {
+                            DEBUG_r(accepted_word=aho->states[ state ].wordnum);
                             leftmost = lpos;
+                        }
                     }
-                    DEBUG_TRIE_EXECUTE_r(
-                        PerlIO_printf( Perl_debug_log,
-                            "%sState: %4"UVxf", Base: 0x%-4"UVxf" uvc=%"UVxf"\n",
-                            "All done: ",
-                            state, base, uvc)
-                    );
                     if (leftmost) {
                         s = (char*)leftmost;
+                        DEBUG_TRIE_EXECUTE_r({
+                            PerlIO_printf( 
+                                Perl_debug_log,"Matches word #%"UVxf" at position %d. Trying full pattern...\n",
+                                (UV)accepted_word, s - real_start
+                            );
+                        });
                         if (!reginfo || regtry(reginfo, s)) {
                             FREETMPS;
                            LEAVE;
                             goto got_it;
                         }
                         s = HOPc(s,1);
+                        DEBUG_TRIE_EXECUTE_r({
+                            PerlIO_printf( Perl_debug_log,"Pattern failed. Looking for new start point...\n");
+                        });
                     } else {
+                        DEBUG_TRIE_EXECUTE_r(
+                            PerlIO_printf( Perl_debug_log,"No match.\n"));
                         break;
                     }
                 }
@@ -1529,14 +1656,20 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
     reginfo.prog = prog;
 
     RX_MATCH_UTF8_set(prog, do_utf8);
+    DEBUG_EXECUTE_r( 
+        debug_start_match(prog, do_utf8, startpos, strend, 
+        "Matching");
+    );
 
     minlen = prog->minlen;
-    if (strend - startpos < minlen) {
+    
+    if (strend - startpos < (minlen+(prog->check_offset_min<0?prog->check_offset_min:0))) {
         DEBUG_EXECUTE_r(PerlIO_printf(Perl_debug_log,
                              "String too short [regexec_flags]...\n"));
        goto phooey;
     }
 
+    
     /* Check validity of program. */
     if (UCHARAT(prog->program) != REG_MAGIC) {
        Perl_croak(aTHX_ "corrupted regexp program");
@@ -1595,10 +1728,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
        }
     }
 
-    DEBUG_EXECUTE_r( 
-        debug_start_match(prog, do_utf8, startpos, strend, 
-            "Matching");
-             );
+
 
     /* Simplest case:  anchored match need be tried only once. */
     /*  [unless only anchor is BOL and multiline is set] */
@@ -1712,14 +1842,19 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
            back_max = prog->float_max_offset;
            back_min = prog->float_min_offset;
        }
+       
+           
        if (must == &PL_sv_undef)
            /* could not downgrade utf8 check substring, so must fail */
            goto phooey;
 
-       last = HOP3c(strend,    /* Cannot start after this */
-                         -(I32)(CHR_SVLEN(must)
-                                - (SvTAIL(must) != 0) + back_min), strbeg);
-
+        if (back_min<0) {
+           last = strend;
+       } else {
+            last = HOP3c(strend,       /* Cannot start after this */
+                 -(I32)(CHR_SVLEN(must)
+                        - (SvTAIL(must) != 0) + back_min), strbeg);
+        }
        if (s > PL_bostr)
            last1 = HOPc(s, -1);
        else
@@ -1732,9 +1867,9 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
        strend = HOPc(strend, -dontbother);
        while ( (s <= last) &&
                ((flags & REXEC_SCREAM)
-                ? (s = screaminstr(sv, must, HOP3c(s, back_min, strend) - strbeg,
+                ? (s = screaminstr(sv, must, HOP3c(s, back_min, (back_min<0 ? strbeg : strend)) - strbeg,
                                    end_shift, &scream_pos, 0))
-                : (s = fbm_instr((unsigned char*)HOP3(s, back_min, strend),
+                : (s = fbm_instr((unsigned char*)HOP3(s, back_min, (back_min<0 ? strbeg : strend)),
                                  (unsigned char*)strend, must,
                                  multiline ? FBMrf_MULTILINE : 0))) ) {
            /* we may be pointing at the wrong string */
@@ -1776,11 +1911,11 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
         });                
        goto phooey;
     }
-    else if ((c = prog->regstclass)) {
+    else if ( (c = prog->regstclass) ) {
        if (minlen) {
            const OPCODE op = OP(prog->regstclass);
            /* don't bother with what can't match */
-           if (PL_regkind[op] != EXACT && op != CANY && op != TRIE)
+           if (PL_regkind[op] != EXACT && op != CANY && PL_regkind[op] != TRIE)
                strend = HOPc(strend, -(minlen - 1));
        }
        DEBUG_EXECUTE_r({
@@ -1791,7 +1926,7 @@ Perl_regexec_flags(pTHX_ register regexp *prog, char *stringarg, register char *
                    s,strend-s,60);
                PerlIO_printf(Perl_debug_log,
                    "Matching stclass %.*s against %s (%d chars)\n",
-                   SvCUR(prop), SvPVX_const(prop),
+                   (int)SvCUR(prop), SvPVX_const(prop),
                     quoted, (int)(strend - s));
            }
        });
@@ -2296,35 +2431,41 @@ S_debug_start_match(pTHX_ const regexp *prog, const bool do_utf8,
                       PL_colors[4], blurb, PL_colors[5], s0, s1); 
         
         if (do_utf8||utf8_pat) 
-            PerlIO_printf(Perl_debug_log, "UTF-8 %s...\n",
-                !do_utf8 ? "pattern" : !utf8_pat ? "string" : 
-                    "pattern and string"
+            PerlIO_printf(Perl_debug_log, "UTF-8 %s%s%s...\n",
+                utf8_pat ? "pattern" : "",
+                utf8_pat && do_utf8 ? " and " : "",
+                do_utf8 ? "string" : ""
             ); 
     }
 }
 
 STATIC void
-S_dump_exec_pos(pTHX_ const char *locinput, const regnode *scan, const bool do_utf8)
+S_dump_exec_pos(pTHX_ const char *locinput, 
+                      const regnode *scan, 
+                      const char *loc_regeol, 
+                      const char *loc_bostr, 
+                      const char *loc_reg_starttry,
+                      const bool do_utf8)
 {
-    const int docolor = *PL_colors[0];
+    const int docolor = *PL_colors[0] || *PL_colors[2] || *PL_colors[4];
     const int taill = (docolor ? 10 : 7); /* 3 chars for "> <" */
-    int l = (PL_regeol - locinput) > taill ? taill : (PL_regeol - locinput);
+    int l = (loc_regeol - locinput) > taill ? taill : (loc_regeol - locinput);
     /* The part of the string before starttry has one color
        (pref0_len chars), between starttry and current
        position another one (pref_len - pref0_len chars),
        after the current position the third one.
        We assume that pref0_len <= pref_len, otherwise we
        decrease pref0_len.  */
-    int pref_len = (locinput - PL_bostr) > (5 + taill) - l
-       ? (5 + taill) - l : locinput - PL_bostr;
+    int pref_len = (locinput - loc_bostr) > (5 + taill) - l
+       ? (5 + taill) - l : locinput - loc_bostr;
     int pref0_len;
 
     while (do_utf8 && UTF8_IS_CONTINUATION(*(U8*)(locinput - pref_len)))
        pref_len++;
-    pref0_len = pref_len  - (locinput - PL_reg_starttry);
-    if (l + pref_len < (5 + taill) && l < PL_regeol - locinput)
-       l = ( PL_regeol - locinput > (5 + taill) - pref_len
-             ? (5 + taill) - pref_len : PL_regeol - locinput);
+    pref0_len = pref_len  - (locinput - loc_reg_starttry);
+    if (l + pref_len < (5 + taill) && l < loc_regeol - locinput)
+       l = ( loc_regeol - locinput > (5 + taill) - pref_len
+             ? (5 + taill) - pref_len : loc_regeol - locinput);
     while (do_utf8 && UTF8_IS_CONTINUATION(*(U8*)(locinput + l)))
        l--;
     if (pref0_len < 0)
@@ -2342,16 +2483,17 @@ S_dump_exec_pos(pTHX_ const char *locinput, const regnode *scan, const bool do_u
                    pref_len - pref0_len, 60, 2, 3);
        
        RE_PV_COLOR_DECL(s2,len2,is_uni,PERL_DEBUG_PAD(2),
-                   locinput, PL_regeol - locinput, 60, 0, 1);
+                   locinput, loc_regeol - locinput, 10, 0, 1);
 
+       const STRLEN tlen=len0+len1+len2;
        PerlIO_printf(Perl_debug_log,
                    "%4"IVdf" <%.*s%.*s%s%.*s>%*s|",
-                   (IV)(locinput - PL_bostr),
+                   (IV)(locinput - loc_bostr),
                    len0, s0,
                    len1, s1,
                    (docolor ? "" : "> <"),
                    len2, s2,
-                   15 - l - pref_len + 1,
+                   tlen > 19 ? 0 :  19 - tlen,
                    "");
     }
 }
@@ -2384,12 +2526,14 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
 
     /* these variables are NOT saved during a recusive RFEGMATCH: */
     register I32 nextchr;   /* is always set to UCHARAT(locinput) */
-    bool result;           /* return value of S_regmatch */
+    bool result = 0;       /* return value of S_regmatch */
     int depth = 0;         /* depth of recursion */
     regmatch_state *yes_state = NULL; /* state to pop to on success of
                                                            subpattern */
     U32 state_num;
     
+    I32 parenfloor = 0;
+
 #ifdef DEBUGGING
     GET_RE_DEBUG_FLAGS_DECL;
     PL_regindent++;
@@ -2417,6 +2561,7 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
     st->sw = 0;
     st->logical = 0;
     st->cc = NULL;
+
     /* Note that nextchr is a byte even in UTF */
     nextchr = UCHARAT(locinput);
     scan = prog;
@@ -2424,14 +2569,16 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
 
         DEBUG_EXECUTE_r( {
            SV * const prop = sv_newmortal();
-           dump_exec_pos( locinput, scan, do_utf8 );
+           regnode *rnext=regnext(scan);
+           DUMP_EXEC_POS( locinput, scan, do_utf8 );
            regprop(rex, prop, scan);
             
            PerlIO_printf(Perl_debug_log,
                    "%3"IVdf":%*s%s(%"IVdf")\n",
                    (IV)(scan - rex->program), PL_regindent*2, "",
                    SvPVX_const(prop),
-                   PL_regkind[OP(scan)] == END ? 0 : (IV)(regnext(scan) - rex->program));
+                   (PL_regkind[OP(scan)] == END || !rnext) ? 
+                       0 : (IV)(rnext - rex->program));
        });
 
        next = scan + NEXT_OFF(scan);
@@ -2512,7 +2659,22 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
 
 #undef  ST
 #define ST st->u.trie
-
+        case TRIEC:
+            /* In this case the charclass data is available inline so
+               we can fail fast without a lot of extra overhead. 
+             */
+            if (scan->flags == EXACT || !do_utf8) {
+                if(!ANYOF_BITMAP_TEST(scan, *locinput)) {
+                    DEBUG_EXECUTE_r(
+                        PerlIO_printf(Perl_debug_log,
+                                 "%*s  %sfailed to match trie start class...%s\n",
+                                 REPORT_CODE_OFF+PL_regindent*2, "", PL_colors[4], PL_colors[5])
+                    );
+                    sayNO_SILENT;
+                    /* NOTREACHED */
+                }                      
+            }
+            /* FALL THROUGH */
        case TRIE:
            {
                 /* what type of TRIE am I? (utf8 makes this contextual) */
@@ -2526,23 +2688,6 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
                    = (reg_trie_data*)rex->data->data[ ARG( scan ) ];
                 U32 state = trie->startstate;
 
-               U8 *uc = ( U8* )locinput;
-               U16 charid = 0;
-               U32 base = 0;
-               UV uvc = 0;
-               STRLEN len = 0;
-               STRLEN foldlen = 0;
-               U8 *uscan = (U8*)NULL;
-               STRLEN bufflen=0;
-               SV *sv_accept_buff = NULL;
-               U8 foldbuf[ UTF8_MAXBYTES_CASE + 1 ];
-
-               ST.accepted = 0; /* how many accepting states we have seen */
-               ST.B = next;
-#ifdef DEBUGGING
-               ST.me = scan;
-#endif
-                
                if (trie->bitmap && trie_type != trie_utf8_fold &&
                    !TRIE_BITMAP_TEST(trie,*locinput)
                ) {
@@ -2556,36 +2701,65 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
                    } else {
                        DEBUG_EXECUTE_r(
                             PerlIO_printf(Perl_debug_log,
-                                         "%*s  %sfailed to match start class...%s\n",
+                                         "%*s  %sfailed to match trie start class...%s\n",
                                          REPORT_CODE_OFF+PL_regindent*2, "", PL_colors[4], PL_colors[5])
                         );
                        sayNO_SILENT;
                   }
                 }
 
+            { 
+               U8 *uc = ( U8* )locinput;
+
+               STRLEN len = 0;
+               STRLEN foldlen = 0;
+               U8 *uscan = (U8*)NULL;
+               STRLEN bufflen=0;
+               SV *sv_accept_buff = NULL;
+               U8 foldbuf[ UTF8_MAXBYTES_CASE + 1 ];
+
+               ST.accepted = 0; /* how many accepting states we have seen */
+               ST.B = next;
+               ST.jump = trie->jump;
+               
+#ifdef DEBUGGING
+               ST.me = scan;
+#endif
+                
+               
+
                /*
                   traverse the TRIE keeping track of all accepting states
                   we transition through until we get to a failing node.
                */
 
                while ( state && uc <= (U8*)PL_regeol ) {
-
-                   if (trie->states[ state ].wordnum) {
-                       if (!ST.accepted ) {
+                    U32 base = trie->states[ state ].trans.base;
+                    UV uvc;
+                    U16 charid;
+                    /* We use charid to hold the wordnum as we don't use it
+                       for charid until after we have done the wordnum logic. 
+                       We define an alias just so that the wordnum logic reads
+                       more naturally. */
+
+#define got_wordnum charid
+                    got_wordnum = trie->states[ state ].wordnum;
+
+                   if ( got_wordnum ) {
+                       if ( ! ST.accepted ) {
                            ENTER;
                            SAVETMPS;
                            bufflen = TRIE_INITAL_ACCEPT_BUFFLEN;
                            sv_accept_buff=newSV(bufflen *
                                            sizeof(reg_trie_accepted) - 1);
-                           SvCUR_set(sv_accept_buff,
-                                               sizeof(reg_trie_accepted));
+                           SvCUR_set(sv_accept_buff, 0);
                            SvPOK_on(sv_accept_buff);
                            sv_2mortal(sv_accept_buff);
                            SAVETMPS;
                            ST.accept_buff =
                                (reg_trie_accepted*)SvPV_nolen(sv_accept_buff );
                        }
-                       else {
+                       do {
                            if (ST.accepted >= bufflen) {
                                bufflen *= 2;
                                ST.accept_buff =(reg_trie_accepted*)
@@ -2594,20 +2768,21 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
                            }
                            SvCUR_set(sv_accept_buff,SvCUR(sv_accept_buff)
                                + sizeof(reg_trie_accepted));
-                       }
-                       ST.accept_buff[ST.accepted].wordnum = trie->states[state].wordnum;
-                       ST.accept_buff[ST.accepted].endpos = uc;
-                       ++ST.accepted;
-                   }
 
-                   base = trie->states[ state ].trans.base;
+
+                           ST.accept_buff[ST.accepted].wordnum = got_wordnum;
+                           ST.accept_buff[ST.accepted].endpos = uc;
+                           ++ST.accepted;
+                       } while (trie->nextword && (got_wordnum= trie->nextword[got_wordnum]));
+                   }
+#undef got_wordnum 
 
                    DEBUG_TRIE_EXECUTE_r({
-                               dump_exec_pos( (char *)uc, scan, do_utf8 );
+                               DUMP_EXEC_POS( (char *)uc, scan, do_utf8 );
                                PerlIO_printf( Perl_debug_log,
-                                   "%*s  %sState: %4"UVxf", Base: %4"UVxf", Accepted: %4"UVxf" ",
+                                   "%*s  %sState: %4"UVxf" Accepted: %4"UVxf" ",
                                    2+PL_regindent * 2, "", PL_colors[4],
-                                   (UV)state, (UV)base, (UV)ST.accepted );
+                                   (UV)state, (UV)ST.accepted );
                    });
 
                    if ( base ) {
@@ -2635,7 +2810,7 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
                    }
                    DEBUG_TRIE_EXECUTE_r(
                        PerlIO_printf( Perl_debug_log,
-                           "Charid:%3x CV:%4"UVxf" After State: %4"UVxf"%s\n",
+                           "Charid:%3x CP:%4"UVxf" After State: %4"UVxf"%s\n",
                            charid, uvc, (UV)state, PL_colors[5] );
                    );
                }
@@ -2648,7 +2823,7 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
                        REPORT_CODE_OFF + PL_regindent * 2, "",
                        PL_colors[4], (IV)ST.accepted, PL_colors[5] );
                );
-           }
+           }}
 
            /* FALL THROUGH */
 
@@ -2676,7 +2851,12 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
                LEAVE;
                locinput = PL_reginput;
                nextchr = UCHARAT(locinput);
-               scan = ST.B;
+               
+               if ( !ST.jump ) 
+                   scan = ST.B;
+               else
+                   scan = ST.B - ST.jump[ST.accept_buff[0].wordnum];
+               
                continue; /* execute rest of RE */
            }
 
@@ -2735,8 +2915,15 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
                    best = ST.accepted;
                }
                PL_reginput = (char *)ST.accept_buff[ best ].endpos;
+               if ( !ST.jump ) {
+                   PUSH_STATE_GOTO(TRIE_next, ST.B);
+                   /* NOTREACHED */
+               } else {
+                   PUSH_STATE_GOTO(TRIE_next, ST.B - ST.jump[ST.accept_buff[best].wordnum]);
+                   /* NOTREACHED */
+                }
+                /* NOTREACHED */
            }
-           PUSH_STATE_GOTO(TRIE_next, ST.B);
            /* NOTREACHED */
 
 #undef  ST
@@ -3228,11 +3415,6 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
                }
 
                /* run the pattern returned from (??{...}) */
-               DEBUG_EXECUTE_r(
-                    debug_start_match(re, do_utf8, locinput, PL_regeol, 
-                        "Matching embedded");
-                   );
-
                ST.cp = regcppush(0);   /* Save *all* the positions. */
                REGCP_SET(ST.lastcp);
                *PL_reglastparen = 0;
@@ -3250,6 +3432,10 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
                rex = re;
 
                ST.B = next;
+               DEBUG_EXECUTE_r(
+                    debug_start_match(re, do_utf8, locinput, PL_regeol, 
+                        "Matching embedded");
+                   );
                /* now continue  from first node in postoned RE */
                PUSH_YES_STATE_GOTO(EVAL_A, re->program + 1);
                /* NOTREACHED */
@@ -3279,7 +3465,6 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
             /* continue at the node following the (??{...}) */
            scan = ST.B;
            continue;
-
        case EVAL_A_fail: /* unsuccessfully ran inner rex (??{rex}) */
            /* Restore state to the outer re then re-throw the failure */
            if (ST.toggleutf)
@@ -3407,8 +3592,8 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
 
        case CURLYX: {
                /* No need to save/restore up to this paren */
-               I32 parenfloor = scan->flags;
-
+               parenfloor = scan->flags;
+               
                /* Dave says:
                   
                   CURLYX and WHILEM are always paired: they're the moral
@@ -4280,6 +4465,7 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
            newst->sw = 0;
            newst->logical = 0;
 
+
            locinput = PL_reginput;
            nextchr = UCHARAT(locinput);
            st = newst;
@@ -4316,6 +4502,7 @@ S_regmatch(pTHX_ const regmatch_info *reginfo, regnode *prog)
            st->minmod = 0;
            st->sw = 0;
            st->logical = 0;
+           
 #ifdef DEBUGGING
            PL_regindent++;
 #endif
@@ -4337,7 +4524,6 @@ yes_final:
     if (yes_state) {
        /* we have successfully completed a subexpression, but we must now
         * pop to the state marked by yes_state and continue from there */
-
        assert(st != yes_state);
        while (yes_state < SLAB_FIRST(PL_regmatch_slab)
            || yes_state > SLAB_LAST(PL_regmatch_slab))
@@ -4348,16 +4534,16 @@ yes_final:
            st = SLAB_LAST(PL_regmatch_slab);
        }
        depth -= (st - yes_state);
-       DEBUG_STATE_r(PerlIO_printf(Perl_debug_log, "POP STATES (%d..%d)\n",
-           depth+1, depth+(st - yes_state)));
+       DEBUG_STATE_r(PerlIO_printf(Perl_debug_log, "POP STATES (%"UVuf"..%"UVuf")\n",
+           (UV)(depth+1), (UV)(depth+(st - yes_state))));
        st = yes_state;
        yes_state = st->u.yes.prev_yes_state;
        PL_regmatch_state = st;
 
        switch (st->resume_state) {
+       case EVAL_A: 
        case IFMATCH_A:
        case CURLYM_A:
-       case EVAL_A:
            state_num = st->resume_state;
            goto reenter_switch;
 
@@ -4432,8 +4618,9 @@ yes:
 no:
     DEBUG_EXECUTE_r(
        PerlIO_printf(Perl_debug_log,
-                     "%*s  %sfailed...%s\n",
-                     REPORT_CODE_OFF+PL_regindent*2, "", PL_colors[4], PL_colors[5])
+            "%*s  %sfailed...%s\n",
+            REPORT_CODE_OFF+PL_regindent*2, "", 
+            PL_colors[4], PL_colors[5])
        );
 no_final:
 do_no:
@@ -4837,7 +5024,7 @@ S_reginclass(pTHX_ const regexp *prog, register const regnode *n, register const
        c = utf8n_to_uvchr(p, UTF8_MAXBYTES, &len,
                (UTF8_ALLOW_DEFAULT & UTF8_ALLOW_ANYUV) | UTF8_CHECK_ONLY);
                /* see [perl #37836] for UTF8_ALLOW_ANYUV */
-       if (len == (STRLEN)-1)
+       if (len == (STRLEN)-1) 
            Perl_croak(aTHX_ "Malformed UTF-8 character (fatal)");
     }
 
@@ -4957,21 +5144,43 @@ S_reghop3(U8 *s, I32 off, const U8* lim)
        }
     }
     else {
-       while (off++) {
-           if (s > lim) {
-               s--;
-               if (UTF8_IS_CONTINUED(*s)) {
-                   while (s > (U8*)lim && UTF8_IS_CONTINUATION(*s))
-                       s--;
-               }
-               /* XXX could check well-formedness here */
+        while (off++ && s > lim) {
+            s--;
+            if (UTF8_IS_CONTINUED(*s)) {
+                while (s > lim && UTF8_IS_CONTINUATION(*s))
+                    s--;
            }
+            /* XXX could check well-formedness here */
        }
     }
     return s;
 }
 
 STATIC U8 *
+S_reghop4(U8 *s, I32 off, const U8* llim, const U8* rlim)
+{
+    dVAR;
+    if (off >= 0) {
+        while (off-- && s < rlim) {
+            /* XXX could check well-formedness here */
+            s += UTF8SKIP(s);
+        }
+    }
+    else {
+        while (off++ && s > llim) {
+            s--;
+            if (UTF8_IS_CONTINUED(*s)) {
+                while (s > llim && UTF8_IS_CONTINUATION(*s))
+                    s--;
+            }
+            /* XXX could check well-formedness here */
+        }
+    }
+    return s;
+}
+
+
+STATIC U8 *
 S_reghopmaybe3(U8* s, I32 off, const U8* lim)
 {
     dVAR;
@@ -4984,17 +5193,13 @@ S_reghopmaybe3(U8* s, I32 off, const U8* lim)
            return NULL;
     }
     else {
-       while (off++) {
-           if (s > lim) {
-               s--;
-               if (UTF8_IS_CONTINUED(*s)) {
-                   while (s > (U8*)lim && UTF8_IS_CONTINUATION(*s))
-                       s--;
-               }
-               /* XXX could check well-formedness here */
+        while (off++ && s > lim) {
+            s--;
+            if (UTF8_IS_CONTINUED(*s)) {
+                while (s > lim && UTF8_IS_CONTINUATION(*s))
+                    s--;
            }
-           else
-               break;
+            /* XXX could check well-formedness here */
        }
        if (off <= 0)
            return NULL;