/[pcre]/code/trunk/pcre_dfa_exec.c
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Diff of /code/trunk/pcre_dfa_exec.c

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revision 428 by ph10, Mon Aug 31 17:10:26 2009 UTC revision 462 by ph10, Sat Oct 17 19:55:02 2009 UTC
# Line 45  FSM). This is NOT Perl- compatible, but Line 45  FSM). This is NOT Perl- compatible, but
45  applications. */  applications. */
46    
47    
48    /* NOTE ABOUT PERFORMANCE: A user of this function sent some code that improved
49    the performance of his patterns greatly. I could not use it as it stood, as it
50    was not thread safe, and made assumptions about pattern sizes. Also, it caused
51    test 7 to loop, and test 9 to crash with a segfault.
52    
53    The issue is the check for duplicate states, which is done by a simple linear
54    search up the state list. (Grep for "duplicate" below to find the code.) For
55    many patterns, there will never be many states active at one time, so a simple
56    linear search is fine. In patterns that have many active states, it might be a
57    bottleneck. The suggested code used an indexing scheme to remember which states
58    had previously been used for each character, and avoided the linear search when
59    it knew there was no chance of a duplicate. This was implemented when adding
60    states to the state lists.
61    
62    I wrote some thread-safe, not-limited code to try something similar at the time
63    of checking for duplicates (instead of when adding states), using index vectors
64    on the stack. It did give a 13% improvement with one specially constructed
65    pattern for certain subject strings, but on other strings and on many of the
66    simpler patterns in the test suite it did worse. The major problem, I think,
67    was the extra time to initialize the index. This had to be done for each call
68    of internal_dfa_exec(). (The supplied patch used a static vector, initialized
69    only once - I suspect this was the cause of the problems with the tests.)
70    
71    Overall, I concluded that the gains in some cases did not outweigh the losses
72    in others, so I abandoned this code. */
73    
74    
75    
76  #ifdef HAVE_CONFIG_H  #ifdef HAVE_CONFIG_H
77  #include "config.h"  #include "config.h"
78  #endif  #endif
# Line 81  never stored, so we push them well clear Line 109  never stored, so we push them well clear
109  character that is to be tested in some way. This makes is possible to  character that is to be tested in some way. This makes is possible to
110  centralize the loading of these characters. In the case of Type * etc, the  centralize the loading of these characters. In the case of Type * etc, the
111  "character" is the opcode for \D, \d, \S, \s, \W, or \w, which will always be a  "character" is the opcode for \D, \d, \S, \s, \W, or \w, which will always be a
112  small value. ***NOTE*** If the start of this table is modified, the two tables  small value. Non-zero values in the table are the offsets from the opcode where
113  that follow must also be modified. */  the character is to be found. ***NOTE*** If the start of this table is
114    modified, the three tables that follow must also be modified. */
115    
116  static const uschar coptable[] = {  static const uschar coptable[] = {
117    0,                             /* End                                    */    0,                             /* End                                    */
# Line 132  static const uschar coptable[] = { Line 161  static const uschar coptable[] = {
161    0,                             /* DEF                                    */    0,                             /* DEF                                    */
162    0, 0,                          /* BRAZERO, BRAMINZERO                    */    0, 0,                          /* BRAZERO, BRAMINZERO                    */
163    0, 0, 0, 0,                    /* PRUNE, SKIP, THEN, COMMIT              */    0, 0, 0, 0,                    /* PRUNE, SKIP, THEN, COMMIT              */
164    0, 0, 0                        /* FAIL, ACCEPT, SKIPZERO                 */    0, 0, 0, 0                     /* FAIL, ACCEPT, CLOSE, SKIPZERO          */
165    };
166    
167    /* This table identifies those opcodes that inspect a character. It is used to
168    remember the fact that a character could have been inspected when the end of
169    the subject is reached, in order to support PCRE_PARTIAL_HARD behaviour.
170    ***NOTE*** If the start of this table is modified, the two tables that follow
171    must also be modified. */
172    
173    static const uschar poptable[] = {
174      0,                             /* End                                    */
175      0, 0, 0, 0, 0,                 /* \A, \G, \K, \B, \b                     */
176      1, 1, 1, 1, 1, 1,              /* \D, \d, \S, \s, \W, \w                 */
177      1, 1, 1,                       /* Any, AllAny, Anybyte                   */
178      1, 1, 1,                       /* NOTPROP, PROP, EXTUNI                  */
179      1, 1, 1, 1, 1,                 /* \R, \H, \h, \V, \v                     */
180      0, 0, 0, 0, 0,                 /* \Z, \z, Opt, ^, $                      */
181      1,                             /* Char                                   */
182      1,                             /* Charnc                                 */
183      1,                             /* not                                    */
184      /* Positive single-char repeats                                          */
185      1, 1, 1, 1, 1, 1,              /* *, *?, +, +?, ?, ??                    */
186      1, 1, 1,                       /* upto, minupto, exact                   */
187      1, 1, 1, 1,                    /* *+, ++, ?+, upto+                      */
188      /* Negative single-char repeats - only for chars < 256                   */
189      1, 1, 1, 1, 1, 1,              /* NOT *, *?, +, +?, ?, ??                */
190      1, 1, 1,                       /* NOT upto, minupto, exact               */
191      1, 1, 1, 1,                    /* NOT *+, ++, ?+, upto+                  */
192      /* Positive type repeats                                                 */
193      1, 1, 1, 1, 1, 1,              /* Type *, *?, +, +?, ?, ??               */
194      1, 1, 1,                       /* Type upto, minupto, exact              */
195      1, 1, 1, 1,                    /* Type *+, ++, ?+, upto+                 */
196      /* Character class & ref repeats                                         */
197      1, 1, 1, 1, 1, 1,              /* *, *?, +, +?, ?, ??                    */
198      1, 1,                          /* CRRANGE, CRMINRANGE                    */
199      1,                             /* CLASS                                  */
200      1,                             /* NCLASS                                 */
201      1,                             /* XCLASS - variable length               */
202      0,                             /* REF                                    */
203      0,                             /* RECURSE                                */
204      0,                             /* CALLOUT                                */
205      0,                             /* Alt                                    */
206      0,                             /* Ket                                    */
207      0,                             /* KetRmax                                */
208      0,                             /* KetRmin                                */
209      0,                             /* Assert                                 */
210      0,                             /* Assert not                             */
211      0,                             /* Assert behind                          */
212      0,                             /* Assert behind not                      */
213      0,                             /* Reverse                                */
214      0, 0, 0, 0,                    /* ONCE, BRA, CBRA, COND                  */
215      0, 0, 0,                       /* SBRA, SCBRA, SCOND                     */
216      0,                             /* CREF                                   */
217      0,                             /* RREF                                   */
218      0,                             /* DEF                                    */
219      0, 0,                          /* BRAZERO, BRAMINZERO                    */
220      0, 0, 0, 0,                    /* PRUNE, SKIP, THEN, COMMIT              */
221      0, 0, 0, 0                     /* FAIL, ACCEPT, CLOSE, SKIPZERO          */
222  };  };
223    
224  /* These 2 tables allow for compact code for testing for \D, \d, \S, \s, \W,  /* These 2 tables allow for compact code for testing for \D, \d, \S, \s, \W,
# Line 390  if (*first_op == OP_REVERSE) Line 476  if (*first_op == OP_REVERSE)
476      current_subject -= gone_back;      current_subject -= gone_back;
477      }      }
478    
479      /* Save the earliest consulted character */
480    
481      if (current_subject < md->start_used_ptr)
482        md->start_used_ptr = current_subject;
483    
484    /* Now we can process the individual branches. */    /* Now we can process the individual branches. */
485    
486    end_code = this_start_code;    end_code = this_start_code;
# Line 455  for (;;) Line 546  for (;;)
546    int clen, dlen;    int clen, dlen;
547    unsigned int c, d;    unsigned int c, d;
548    int forced_fail = 0;    int forced_fail = 0;
549    int reached_end = 0;    int reached_end = 0;
550      BOOL could_continue = FALSE;
551    
552    /* Make the new state list into the active state list and empty the    /* Make the new state list into the active state list and empty the
553    new state list. */    new state list. */
# Line 545  for (;;) Line 637  for (;;)
637          }          }
638        }        }
639    
640      /* Check for a duplicate state with the same count, and skip if found. */      /* Check for a duplicate state with the same count, and skip if found.
641        See the note at the head of this module about the possibility of improving
642        performance here. */
643    
644      for (j = 0; j < i; j++)      for (j = 0; j < i; j++)
645        {        {
# Line 561  for (;;) Line 655  for (;;)
655    
656      code = start_code + state_offset;      code = start_code + state_offset;
657      codevalue = *code;      codevalue = *code;
658    
659        /* If this opcode inspects a character, but we are at the end of the
660        subject, remember the fact so that we can support PCRE_PARTIAL_HARD. */
661    
662        if (clen == 0 && poptable[codevalue] != 0)
663          could_continue = TRUE;
664    
665      /* If this opcode is followed by an inline character, load it. It is      /* If this opcode is followed by an inline character, load it. It is
666      tempting to test for the presence of a subject character here, but that      tempting to test for the presence of a subject character here, but that
# Line 612  for (;;) Line 712  for (;;)
712  /* ========================================================================== */  /* ========================================================================== */
713        /* Reached a closing bracket. If not at the end of the pattern, carry        /* Reached a closing bracket. If not at the end of the pattern, carry
714        on with the next opcode. Otherwise, unless we have an empty string and        on with the next opcode. Otherwise, unless we have an empty string and
715        PCRE_NOTEMPTY is set, save the match data, shifting up all previous        PCRE_NOTEMPTY is set, or PCRE_NOTEMPTY_ATSTART is set and we are at the
716          start of the subject, save the match data, shifting up all previous
717        matches so we always have the longest first. */        matches so we always have the longest first. */
718    
719        case OP_KET:        case OP_KET:
# Line 626  for (;;) Line 727  for (;;)
727            ADD_ACTIVE(state_offset - GET(code, 1), 0);            ADD_ACTIVE(state_offset - GET(code, 1), 0);
728            }            }
729          }          }
730        else        else
731          {          {
732          reached_end++;    /* Count branches that reach the end */          reached_end++;    /* Count branches that reach the end */
733          if (ptr > current_subject || (md->moptions & PCRE_NOTEMPTY) == 0)          if (ptr > current_subject ||
734                ((md->moptions & PCRE_NOTEMPTY) == 0 &&
735                  ((md->moptions & PCRE_NOTEMPTY_ATSTART) == 0 ||
736                    current_subject > start_subject + md->start_offset)))
737            {            {
738            if (match_count < 0) match_count = (offsetcount >= 2)? 1 : 0;            if (match_count < 0) match_count = (offsetcount >= 2)? 1 : 0;
739              else if (match_count > 0 && ++match_count * 2 >= offsetcount)              else if (match_count > 0 && ++match_count * 2 >= offsetcount)
# Line 650  for (;;) Line 754  for (;;)
754                match_count, rlevel*2-2, SP));                match_count, rlevel*2-2, SP));
755              return match_count;              return match_count;
756              }              }
757            }            }
758          }          }
759        break;        break;
760    
# Line 800  for (;;) Line 904  for (;;)
904          if (ptr > start_subject)          if (ptr > start_subject)
905            {            {
906            const uschar *temp = ptr - 1;            const uschar *temp = ptr - 1;
907              if (temp < md->start_used_ptr) md->start_used_ptr = temp;
908  #ifdef SUPPORT_UTF8  #ifdef SUPPORT_UTF8
909            if (utf8) BACKCHAR(temp);            if (utf8) BACKCHAR(temp);
910  #endif  #endif
# Line 808  for (;;) Line 913  for (;;)
913            }            }
914          else left_word = 0;          else left_word = 0;
915    
916          if (clen > 0)          if (clen > 0)
917            right_word = c < 256 && (ctypes[c] & ctype_word) != 0;            right_word = c < 256 && (ctypes[c] & ctype_word) != 0;
918          else              /* This is a fudge to ensure that if this is the */          else              /* This is a fudge to ensure that if this is the */
919            {               /* last item in the pattern, we don't count it as */            {               /* last item in the pattern, we don't count it as */
920            reached_end--;  /* reached, thus disabling a partial match. */            reached_end--;  /* reached, thus disabling a partial match. */
921            right_word = 0;            right_word = 0;
922            }            }
923    
924          if ((left_word == right_word) == (codevalue == OP_NOT_WORD_BOUNDARY))          if ((left_word == right_word) == (codevalue == OP_NOT_WORD_BOUNDARY))
925            { ADD_ACTIVE(state_offset + 1, 0); }            { ADD_ACTIVE(state_offset + 1, 0); }
# Line 2247  for (;;) Line 2352  for (;;)
2352    
2353          /* Back reference conditions are not supported */          /* Back reference conditions are not supported */
2354    
2355          if (condcode == OP_CREF) return PCRE_ERROR_DFA_UCOND;          if (condcode == OP_CREF || condcode == OP_NCREF)
2356              return PCRE_ERROR_DFA_UCOND;
2357    
2358          /* The DEFINE condition is always false */          /* The DEFINE condition is always false */
2359    
# Line 2258  for (;;) Line 2364  for (;;)
2364          which means "test if in any recursion". We can't test for specifically          which means "test if in any recursion". We can't test for specifically
2365          recursed groups. */          recursed groups. */
2366    
2367          else if (condcode == OP_RREF)          else if (condcode == OP_RREF || condcode == OP_NRREF)
2368            {            {
2369            int value = GET2(code, LINK_SIZE+2);            int value = GET2(code, LINK_SIZE+2);
2370            if (value != RREF_ANY) return PCRE_ERROR_DFA_UCOND;            if (value != RREF_ANY) return PCRE_ERROR_DFA_UCOND;
# Line 2481  for (;;) Line 2587  for (;;)
2587    /* We have finished the processing at the current subject character. If no    /* We have finished the processing at the current subject character. If no
2588    new states have been set for the next character, we have found all the    new states have been set for the next character, we have found all the
2589    matches that we are going to find. If we are at the top level and partial    matches that we are going to find. If we are at the top level and partial
2590    matching has been requested, check for appropriate conditions. The "forced_    matching has been requested, check for appropriate conditions.
2591    fail" variable counts the number of (*F) encountered for the character. If it  
2592    is equal to the original active_count (saved in workspace[1]) it means that    The "forced_ fail" variable counts the number of (*F) encountered for the
2593    (*F) was found on every active state. In this case we don't want to give a    character. If it is equal to the original active_count (saved in
2594    partial match. */    workspace[1]) it means that (*F) was found on every active state. In this
2595      case we don't want to give a partial match.
2596    
2597      The "reached_end" variable counts the number of threads that have reached the
2598      end of the pattern. The "could_continue" variable is true if a thread could
2599      have continued but for the fact that the end of the subject was reached. */
2600    
2601    if (new_count <= 0)    if (new_count <= 0)
2602      {      {
2603      if (rlevel == 1 &&                               /* Top level, and */      if (rlevel == 1 &&                               /* Top level, and */
2604          reached_end != workspace[1] &&               /* Not all reached end */          (                                            /* either... */
2605            reached_end != workspace[1] ||               /* Not all reached end */
2606              could_continue                             /* or some could go on */
2607            ) &&                                         /* and... */
2608          forced_fail != workspace[1] &&               /* Not all forced fail & */          forced_fail != workspace[1] &&               /* Not all forced fail & */
2609          (                                            /* either... */          (                                            /* either... */
2610          (md->moptions & PCRE_PARTIAL_HARD) != 0      /* Hard partial */          (md->moptions & PCRE_PARTIAL_HARD) != 0      /* Hard partial */
# Line 2503  for (;;) Line 2617  for (;;)
2617        {        {
2618        if (offsetcount >= 2)        if (offsetcount >= 2)
2619          {          {
2620          offsets[0] = current_subject - start_subject;          offsets[0] = md->start_used_ptr - start_subject;
2621          offsets[1] = end_subject - start_subject;          offsets[1] = end_subject - start_subject;
2622          }          }
2623        match_count = PCRE_ERROR_PARTIAL;        match_count = PCRE_ERROR_PARTIAL;
# Line 2645  md->start_code = (const uschar *)argumen Line 2759  md->start_code = (const uschar *)argumen
2759      re->name_table_offset + re->name_count * re->name_entry_size;      re->name_table_offset + re->name_count * re->name_entry_size;
2760  md->start_subject = (const unsigned char *)subject;  md->start_subject = (const unsigned char *)subject;
2761  md->end_subject = end_subject;  md->end_subject = end_subject;
2762    md->start_offset = start_offset;
2763  md->moptions = options;  md->moptions = options;
2764  md->poptions = re->options;  md->poptions = re->options;
2765    
# Line 2749  if (!anchored) Line 2864  if (!anchored)
2864      }      }
2865    else    else
2866      {      {
2867      if (startline && study != NULL &&      if (!startline && study != NULL &&
2868           (study->options & PCRE_STUDY_MAPPED) != 0)           (study->flags & PCRE_STUDY_MAPPED) != 0)
2869        start_bits = study->start_bits;        start_bits = study->start_bits;
2870      }      }
2871    }    }
# Line 2801  for (;;) Line 2916  for (;;)
2916        }        }
2917    
2918      /* There are some optimizations that avoid running the match if a known      /* There are some optimizations that avoid running the match if a known
2919      starting point is not found, or if a known later character is not present.      starting point is not found. However, there is an option that disables
2920      However, there is an option that disables these, for testing and for      these, for testing and for ensuring that all callouts do actually occur. */
     ensuring that all callouts do actually occur. */  
2921    
2922      if ((options & PCRE_NO_START_OPTIMIZE) == 0)      if ((options & PCRE_NO_START_OPTIMIZE) == 0)
2923        {        {
   
2924        /* Advance to a known first byte. */        /* Advance to a known first byte. */
2925    
2926        if (first_byte >= 0)        if (first_byte >= 0)
# Line 2873  for (;;) Line 2986  for (;;)
2986      /* Restore fudged end_subject */      /* Restore fudged end_subject */
2987    
2988      end_subject = save_end_subject;      end_subject = save_end_subject;
     }  
2989    
2990    /* If req_byte is set, we know that that character must appear in the subject      /* The following two optimizations are disabled for partial matching or if
2991    for the match to succeed. If the first character is set, req_byte must be      disabling is explicitly requested (and of course, by the test above, this
2992    later in the subject; otherwise the test starts at the match point. This      code is not obeyed when restarting after a partial match). */
   optimization can save a huge amount of work in patterns with nested unlimited  
   repeats that aren't going to match. Writing separate code for cased/caseless  
   versions makes it go faster, as does using an autoincrement and backing off  
   on a match.  
   
   HOWEVER: when the subject string is very, very long, searching to its end can  
   take a long time, and give bad performance on quite ordinary patterns. This  
   showed up when somebody was matching /^C/ on a 32-megabyte string... so we  
   don't do this when the string is sufficiently long.  
   
   ALSO: this processing is disabled when partial matching is requested, and can  
   also be explicitly deactivated. Furthermore, we have to disable when  
   restarting after a partial match, because the required character may have  
   already been matched. */  
   
   if ((options & PCRE_NO_START_OPTIMIZE) == 0 &&  
       req_byte >= 0 &&  
       end_subject - current_subject < REQ_BYTE_MAX &&  
       (options & (PCRE_PARTIAL_HARD|PCRE_PARTIAL_SOFT|PCRE_DFA_RESTART)) == 0)  
     {  
     register const uschar *p = current_subject + ((first_byte >= 0)? 1 : 0);  
   
     /* We don't need to repeat the search if we haven't yet reached the  
     place we found it at last time. */  
2993    
2994      if (p > req_byte_ptr)      if ((options & PCRE_NO_START_OPTIMIZE) == 0 &&
2995            (options & (PCRE_PARTIAL_HARD|PCRE_PARTIAL_SOFT)) == 0)
2996        {        {
2997        if (req_byte_caseless)        /* If the pattern was studied, a minimum subject length may be set. This
2998          {        is a lower bound; no actual string of that length may actually match the
2999          while (p < end_subject)        pattern. Although the value is, strictly, in characters, we treat it as
3000            {        bytes to avoid spending too much time in this optimization. */
3001            register int pp = *p++;  
3002            if (pp == req_byte || pp == req_byte2) { p--; break; }        if (study != NULL && (study->flags & PCRE_STUDY_MINLEN) != 0 &&
3003            }            end_subject - current_subject < study->minlength)
3004          }          return PCRE_ERROR_NOMATCH;
3005        else  
3006          /* If req_byte is set, we know that that character must appear in the
3007          subject for the match to succeed. If the first character is set, req_byte
3008          must be later in the subject; otherwise the test starts at the match
3009          point. This optimization can save a huge amount of work in patterns with
3010          nested unlimited repeats that aren't going to match. Writing separate
3011          code for cased/caseless versions makes it go faster, as does using an
3012          autoincrement and backing off on a match.
3013    
3014          HOWEVER: when the subject string is very, very long, searching to its end
3015          can take a long time, and give bad performance on quite ordinary
3016          patterns. This showed up when somebody was matching /^C/ on a 32-megabyte
3017          string... so we don't do this when the string is sufficiently long. */
3018    
3019          if (req_byte >= 0 && end_subject - current_subject < REQ_BYTE_MAX)
3020          {          {
3021          while (p < end_subject)          register const uschar *p = current_subject + ((first_byte >= 0)? 1 : 0);
3022    
3023            /* We don't need to repeat the search if we haven't yet reached the
3024            place we found it at last time. */
3025    
3026            if (p > req_byte_ptr)
3027            {            {
3028            if (*p++ == req_byte) { p--; break; }            if (req_byte_caseless)
3029            }              {
3030          }              while (p < end_subject)
3031                  {
3032                  register int pp = *p++;
3033                  if (pp == req_byte || pp == req_byte2) { p--; break; }
3034                  }
3035                }
3036              else
3037                {
3038                while (p < end_subject)
3039                  {
3040                  if (*p++ == req_byte) { p--; break; }
3041                  }
3042                }
3043    
3044        /* If we can't find the required character, break the matching loop,            /* If we can't find the required character, break the matching loop,
3045        which will cause a return or PCRE_ERROR_NOMATCH. */            which will cause a return or PCRE_ERROR_NOMATCH. */
3046    
3047        if (p >= end_subject) break;            if (p >= end_subject) break;
3048    
3049        /* If we have found the required character, save the point where we            /* If we have found the required character, save the point where we
3050        found it, so that we don't search again next time round the loop if            found it, so that we don't search again next time round the loop if
3051        the start hasn't passed this character yet. */            the start hasn't passed this character yet. */
3052    
3053        req_byte_ptr = p;            req_byte_ptr = p;
3054              }
3055            }
3056        }        }
3057      }      }   /* End of optimizations that are done when not restarting */
3058    
3059    /* OK, now we can do the business */    /* OK, now we can do the business */
3060    
3061      md->start_used_ptr = current_subject;
3062    
3063    rc = internal_dfa_exec(    rc = internal_dfa_exec(
3064      md,                                /* fixed match data */      md,                                /* fixed match data */
3065      md->start_code,                    /* this subexpression's code */      md->start_code,                    /* this subexpression's code */

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