To: vim_dev@googlegroups.com

Subject: Patch 7.4.497

Fcc: outbox

From: Bram Moolenaar <Bram@moolenaar.net>

Mime-Version: 1.0

Content-Type: text/plain; charset=UTF-8

Content-Transfer-Encoding: 8bit

------------

Patch 7.4.497

Problem:    With some regexp patterns the NFA engine uses many states and

	    becomes very slow.  To the user it looks like Vim freezes.

Solution:   When the number of states reaches a limit fall back to the old

	    engine. (Christian Brabandt)

Files:	    runtime/doc/options.txt, src/Makefile, src/regexp.c, src/regexp.h,

	    src/regexp_nfa.c, src/testdir/Make_dos.mak,

	    src/testdir/Make_ming.mak, src/testdir/Make_os2.mak,

	    src/testdir/Makefile, src/testdir/samples/re.freeze.txt,

	    src/testdir/bench_re_freeze.in, src/testdir/bench_re_freeze.vim,

	    Filelist

*** ../vim-7.4.496/runtime/doc/options.txt	2014-09-23 15:45:04.866801055 +0200

--- runtime/doc/options.txt	2014-11-05 12:06:16.664961112 +0100

***************

*** 5622,5627 ****

--- 5626,5635 ----

  	Note that when using the NFA engine and the pattern contains something

  	that is not supported the pattern will not match.  This is only useful

  	for debugging the regexp engine.

+ 	Using automatic selection enables Vim to switch the engine, if the

+ 	default engine becomes too costly.  E.g., when the NFA engine uses too

+ 	many states.  This should prevent Vim from hanging on a combination of

+ 	a complex pattern with long text.

  		*'relativenumber'* *'rnu'* *'norelativenumber'* *'nornu'*

  'relativenumber' 'rnu'	boolean	(default off)

*** ../vim-7.4.496/src/Makefile	2014-08-17 17:05:39.155057796 +0200

--- src/Makefile	2014-11-05 12:01:58.704967328 +0100

***************

*** 1879,1884 ****

--- 1879,1887 ----

  	cd testdir; $(MAKE) -f Makefile $(GUI_TESTTARGET) VIMPROG=../$(VIMTARGET) $(GUI_TESTARG) SCRIPTSOURCE=../$(SCRIPTSOURCE)

  	$(MAKE) -f Makefile unittest

+ benchmark:

+ 	cd testdir; $(MAKE) -f Makefile benchmark VIMPROG=../$(VIMTARGET) SCRIPTSOURCE=../$(SCRIPTSOURCE)

+ 

  unittesttargets:

  	$(MAKE) -f Makefile $(UNITTEST_TARGETS)

*** ../vim-7.4.496/src/regexp.c	2014-09-09 17:18:44.008540299 +0200

--- src/regexp.c	2014-11-05 14:05:40.544788489 +0100

***************

*** 8011,8023 ****

      bt_regcomp,

      bt_regfree,

      bt_regexec_nl,

!     bt_regexec_multi

! #ifdef DEBUG

!     ,(char_u *)""

! #endif

  };

- 

  #include "regexp_nfa.c"

  static regengine_T nfa_regengine =

--- 8011,8020 ----

      bt_regcomp,

      bt_regfree,

      bt_regexec_nl,

!     bt_regexec_multi,

!     (char_u *)""

  };

  #include "regexp_nfa.c"

  static regengine_T nfa_regengine =

***************

*** 8025,8042 ****

      nfa_regcomp,

      nfa_regfree,

      nfa_regexec_nl,

!     nfa_regexec_multi

! #ifdef DEBUG

!     ,(char_u *)""

! #endif

  };

  /* Which regexp engine to use? Needed for vim_regcomp().

   * Must match with 'regexpengine'. */

  static int regexp_engine = 0;

! #define	    AUTOMATIC_ENGINE	0

! #define	    BACKTRACKING_ENGINE	1

! #define	    NFA_ENGINE		2

  #ifdef DEBUG

  static char_u regname[][30] = {

  		    "AUTOMATIC Regexp Engine",

--- 8022,8035 ----

      nfa_regcomp,

      nfa_regfree,

      nfa_regexec_nl,

!     nfa_regexec_multi,

!     (char_u *)""

  };

  /* Which regexp engine to use? Needed for vim_regcomp().

   * Must match with 'regexpengine'. */

  static int regexp_engine = 0;

! 

  #ifdef DEBUG

  static char_u regname[][30] = {

  		    "AUTOMATIC Regexp Engine",

***************

*** 8083,8092 ****

  	    regexp_engine = AUTOMATIC_ENGINE;

  	}

      }

- #ifdef DEBUG

      bt_regengine.expr = expr;

      nfa_regengine.expr = expr;

- #endif

      /*

       * First try the NFA engine, unless backtracking was requested.

--- 8076,8083 ----

***************

*** 8096,8102 ****

      else

  	prog = bt_regengine.regcomp(expr, re_flags);

!     if (prog == NULL)	    /* error compiling regexp with initial engine */

      {

  #ifdef BT_REGEXP_DEBUG_LOG

  	if (regexp_engine != BACKTRACKING_ENGINE)   /* debugging log for NFA */

--- 8087,8094 ----

      else

  	prog = bt_regengine.regcomp(expr, re_flags);

!     /* Check for error compiling regexp with initial engine. */

!     if (prog == NULL)

      {

  #ifdef BT_REGEXP_DEBUG_LOG

  	if (regexp_engine != BACKTRACKING_ENGINE)   /* debugging log for NFA */

***************

*** 8114,8126 ****

  	}

  #endif

  	/*

! 	 * If the NFA engine failed, the backtracking engine won't work either.

  	 *

  	if (regexp_engine == AUTOMATIC_ENGINE)

  	    prog = bt_regengine.regcomp(expr, re_flags);

  	 */

      }

      return prog;

  }

--- 8106,8132 ----

  	}

  #endif

  	/*

! 	 * If the NFA engine failed, try the backtracking engine.

! 	 * Disabled for now, both engines fail on the same patterns.

! 	 * Re-enable when regcomp() fails when the pattern would work better

! 	 * with the other engine.

  	 *

  	if (regexp_engine == AUTOMATIC_ENGINE)

+ 	{

  	    prog = bt_regengine.regcomp(expr, re_flags);

+ 	    regexp_engine == BACKTRACKING_ENGINE;

+ 	}

  	 */

      }

+     if (prog != NULL)

+     {

+ 	/* Store the info needed to call regcomp() again when the engine turns

+ 	 * out to be very slow when executing it. */

+ 	prog->re_engine = regexp_engine;

+ 	prog->re_flags  = re_flags;

+     }

+ 

      return prog;

  }

***************

*** 8135,8154 ****

  	prog->engine->regfree(prog);

  }

  /*

   * Match a regexp against a string.

   * "rmp->regprog" is a compiled regexp as returned by vim_regcomp().

   * Uses curbuf for line count and 'iskeyword'.

   *

   * Return TRUE if there is a match, FALSE if not.

   */

      int

  vim_regexec(rmp, line, col)

!     regmatch_T *rmp;

!     char_u      *line;  /* string to match against */

!     colnr_T     col;    /* column to start looking for match */

  {

!     return rmp->regprog->engine->regexec_nl(rmp, line, col, FALSE);

  }

  #if defined(FEAT_MODIFY_FNAME) || defined(FEAT_EVAL) \

--- 8141,8215 ----

  	prog->engine->regfree(prog);

  }

+ #ifdef FEAT_EVAL

+ static void report_re_switch __ARGS((char_u *pat));

+ 

+     static void

+ report_re_switch(pat)

+     char_u *pat;

+ {

+     if (p_verbose > 0)

+     {

+ 	verbose_enter();

+ 	MSG_PUTS(_("Switching to backtracking RE engine for pattern: "));

+ 	MSG_PUTS(pat);

+ 	verbose_leave();

+     }

+ }

+ #endif

+ 

+ static int vim_regexec_both __ARGS((regmatch_T *rmp, char_u *line, colnr_T col, int nl));

+ 

  /*

   * Match a regexp against a string.

   * "rmp->regprog" is a compiled regexp as returned by vim_regcomp().

   * Uses curbuf for line count and 'iskeyword'.

+  * When "nl" is TRUE consider a "\n" in "line" to be a line break.

   *

   * Return TRUE if there is a match, FALSE if not.

   */

+     static int

+ vim_regexec_both(rmp, line, col, nl)

+     regmatch_T	*rmp;

+     char_u	*line;  /* string to match against */

+     colnr_T	col;    /* column to start looking for match */

+     int		nl;

+ {

+     int result = rmp->regprog->engine->regexec_nl(rmp, line, col, nl);

+ 

+     /* NFA engine aborted because it's very slow. */

+     if (rmp->regprog->re_engine == AUTOMATIC_ENGINE

+ 					       && result == NFA_TOO_EXPENSIVE)

+     {

+ 	int    save_p_re = p_re;

+ 	int    re_flags = rmp->regprog->re_flags;

+ 	char_u *pat = vim_strsave(((nfa_regprog_T *)rmp->regprog)->pattern);

+ 

+ 	p_re = BACKTRACKING_ENGINE;

+ 	vim_regfree(rmp->regprog);

+ 	if (pat != NULL)

+ 	{

+ #ifdef FEAT_EVAL

+ 	    report_re_switch(pat);

+ #endif

+ 	    rmp->regprog = vim_regcomp(pat, re_flags);

+ 	    if (rmp->regprog != NULL)

+ 		result = rmp->regprog->engine->regexec_nl(rmp, line, col, nl);

+ 	    vim_free(pat);

+ 	}

+ 

+ 	p_re = save_p_re;

+     }

+     return result;

+ }

+ 

      int

  vim_regexec(rmp, line, col)

!     regmatch_T	*rmp;

!     char_u	*line;

!     colnr_T	col;

  {

!     return vim_regexec_both(rmp, line, col, FALSE);

  }

  #if defined(FEAT_MODIFY_FNAME) || defined(FEAT_EVAL) \

***************

*** 8158,8168 ****

   */

      int

  vim_regexec_nl(rmp, line, col)

!     regmatch_T *rmp;

!     char_u *line;

!     colnr_T col;

  {

!     return rmp->regprog->engine->regexec_nl(rmp, line, col, TRUE);

  }

  #endif

--- 8219,8229 ----

   */

      int

  vim_regexec_nl(rmp, line, col)

!     regmatch_T	*rmp;

!     char_u	*line;

!     colnr_T	col;

  {

!     return vim_regexec_both(rmp, line, col, TRUE);

  }

  #endif

***************

*** 8183,8187 ****

      colnr_T     col;            /* column to start looking for match */

      proftime_T	*tm;		/* timeout limit or NULL */

  {

!     return rmp->regprog->engine->regexec_multi(rmp, win, buf, lnum, col, tm);

  }

--- 8244,8275 ----

      colnr_T     col;            /* column to start looking for match */

      proftime_T	*tm;		/* timeout limit or NULL */

  {

!     int result = rmp->regprog->engine->regexec_multi(

! 						rmp, win, buf, lnum, col, tm);

! 

!     /* NFA engine aborted because it's very slow. */

!     if (rmp->regprog->re_engine == AUTOMATIC_ENGINE

! 					       && result == NFA_TOO_EXPENSIVE)

!     {

! 	int    save_p_re = p_re;

! 	int    re_flags = rmp->regprog->re_flags;

! 	char_u *pat = vim_strsave(((nfa_regprog_T *)rmp->regprog)->pattern);

! 

! 	p_re = BACKTRACKING_ENGINE;

! 	vim_regfree(rmp->regprog);

! 	if (pat != NULL)

! 	{

! #ifdef FEAT_EVAL

! 	    report_re_switch(pat);

! #endif

! 	    rmp->regprog = vim_regcomp(pat, re_flags);

! 	    if (rmp->regprog != NULL)

! 		result = rmp->regprog->engine->regexec_multi(

! 						rmp, win, buf, lnum, col, tm);

! 	    vim_free(pat);

! 	}

! 	p_re = save_p_re;

!     }

! 

!     return result;

  }

*** ../vim-7.4.496/src/regexp.h	2014-04-23 19:06:33.702828771 +0200

--- src/regexp.h	2014-11-05 13:09:14.136870089 +0100

***************

*** 27,32 ****

--- 27,44 ----

   */

  #define NFA_MAX_BRACES 20

+ /*

+  * In the NFA engine: how many states are allowed

+  */

+ #define NFA_MAX_STATES 100000

+ #define NFA_TOO_EXPENSIVE -1

+ 

+ /* Which regexp engine to use? Needed for vim_regcomp().

+  * Must match with 'regexpengine'. */

+ #define	    AUTOMATIC_ENGINE	0

+ #define	    BACKTRACKING_ENGINE	1

+ #define	    NFA_ENGINE		2

+ 

  typedef struct regengine regengine_T;

  /*

***************

*** 38,43 ****

--- 50,57 ----

  {

      regengine_T		*engine;

      unsigned		regflags;

+     unsigned		re_engine;   /* automatic, backtracking or nfa engine */

+     unsigned		re_flags;    /* second argument for vim_regcomp() */

  } regprog_T;

  /*

***************

*** 47,55 ****

   */

  typedef struct

  {

!     /* These two members implement regprog_T */

      regengine_T		*engine;

      unsigned		regflags;

      int			regstart;

      char_u		reganch;

--- 61,71 ----

   */

  typedef struct

  {

!     /* These four members implement regprog_T */

      regengine_T		*engine;

      unsigned		regflags;

+     unsigned		re_engine;

+     unsigned		re_flags;    /* second argument for vim_regcomp() */

      int			regstart;

      char_u		reganch;

***************

*** 81,89 ****

   */

  typedef struct

  {

!     /* These two members implement regprog_T */

      regengine_T		*engine;

      unsigned		regflags;

      nfa_state_T		*start;		/* points into state[] */

--- 97,107 ----

   */

  typedef struct

  {

!     /* These three members implement regprog_T */

      regengine_T		*engine;

      unsigned		regflags;

+     unsigned		re_engine;

+     unsigned		re_flags;    /* second argument for vim_regcomp() */

      nfa_state_T		*start;		/* points into state[] */

***************

*** 96,104 ****

  #ifdef FEAT_SYN_HL

      int			reghasz;

  #endif

- #ifdef DEBUG

      char_u		*pattern;

- #endif

      int			nsubexp;	/* number of () */

      int			nstate;

      nfa_state_T		state[1];	/* actually longer.. */

--- 114,120 ----

***************

*** 151,159 ****

      void	(*regfree)(regprog_T *);

      int		(*regexec_nl)(regmatch_T*, char_u*, colnr_T, int);

      long	(*regexec_multi)(regmmatch_T*, win_T*, buf_T*, linenr_T, colnr_T, proftime_T*);

- #ifdef DEBUG

      char_u	*expr;

- #endif

  };

  #endif	/* _REGEXP_H */

--- 167,173 ----

*** ../vim-7.4.496/src/regexp_nfa.c	2014-10-11 12:48:22.541259950 +0200

--- src/regexp_nfa.c	2014-11-05 13:08:43.876870818 +0100

***************

*** 5522,5527 ****

--- 5522,5534 ----

  	nextlist->n = 0;	    /* clear nextlist */

  	nextlist->has_pim = FALSE;

  	++nfa_listid;

+ 	if (prog->re_engine == AUTOMATIC_ENGINE && nfa_listid >= NFA_MAX_STATES)

+ 	{

+ 	    /* too many states, retry with old engine */

+ 	    nfa_match = NFA_TOO_EXPENSIVE;

+ 	    goto theend;

+ 	}

+ 

  	thislist->id = nfa_listid;

  	nextlist->id = nfa_listid + 1;

***************

*** 5704,5709 ****

--- 5711,5721 ----

  			 */

  			result = recursive_regmatch(t->state, NULL, prog,

  						       submatch, m, &listids);

+ 			if (result == NFA_TOO_EXPENSIVE)

+ 			{

+ 			    nfa_match = result;

+ 			    goto theend;

+ 			}

  			/* for \@! and \@

  			 * FALSE */

***************

*** 5817,5822 ****

--- 5829,5839 ----

  		/* First try matching the pattern. */

  		result = recursive_regmatch(t->state, NULL, prog,

  						       submatch, m, &listids);

+ 		if (result == NFA_TOO_EXPENSIVE)

+ 		{

+ 		    nfa_match = result;

+ 		    goto theend;

+ 		}

  		if (result)

  		{

  		    int bytelen;

***************

*** 6760,6765 ****

--- 6777,6783 ----

      int		i;

      regsubs_T	subs, m;

      nfa_state_T	*start = prog->start;

+     int		result;

  #ifdef ENABLE_LOG

      FILE	*f;

  #endif

***************

*** 6791,6798 ****

      clear_sub(&m.synt);

  #endif

!     if (nfa_regmatch(prog, start, &subs, &m) == FALSE)

  	return 0;

      cleanup_subexpr();

      if (REG_MULTI)

--- 6809,6819 ----

      clear_sub(&m.synt);

  #endif

!     result = nfa_regmatch(prog, start, &subs, &m);

!     if (result == FALSE)

  	return 0;

+     else if (result == NFA_TOO_EXPENSIVE)

+ 	return result;

      cleanup_subexpr();

      if (REG_MULTI)

***************

*** 6929,6937 ****

      nfa_nsubexpr = prog->nsubexp;

      nfa_listid = 1;

      nfa_alt_listid = 2;

- #ifdef DEBUG

      nfa_regengine.expr = prog->pattern;

- #endif

      if (prog->reganch && col > 0)

  	return 0L;

--- 6950,6956 ----

***************

*** 6979,6987 ****

      retval = nfa_regtry(prog, col);

- #ifdef DEBUG

      nfa_regengine.expr = NULL;

- #endif

  theend:

      return retval;

--- 6998,7004 ----

***************

*** 7003,7011 ****

      if (expr == NULL)

  	return NULL;

- #ifdef DEBUG

      nfa_regengine.expr = expr;

- #endif

      init_class_tab();

--- 7020,7026 ----

***************

*** 7082,7091 ****

      /* Remember whether this pattern has any \z specials in it. */

      prog->reghasz = re_has_z;

  #endif

- #ifdef DEBUG

      prog->pattern = vim_strsave(expr);

      nfa_regengine.expr = NULL;

- #endif

  out:

      vim_free(post_start);

--- 7097,7104 ----

***************

*** 7099,7107 ****

  #ifdef ENABLE_LOG

      nfa_postfix_dump(expr, FAIL);

  #endif

- #ifdef DEBUG

      nfa_regengine.expr = NULL;

- #endif

      goto out;

  }

--- 7112,7118 ----

***************

*** 7115,7123 ****

      if (prog != NULL)

      {

  	vim_free(((nfa_regprog_T *)prog)->match_text);

- #ifdef DEBUG

  	vim_free(((nfa_regprog_T *)prog)->pattern);

- #endif

  	vim_free(prog);

      }

  }

--- 7126,7132 ----

*** ../vim-7.4.496/src/testdir/Make_dos.mak	2014-10-21 20:57:11.534295006 +0200

--- src/testdir/Make_dos.mak	2014-11-05 14:14:56.536775091 +0100

***************

*** 87,92 ****

--- 87,93 ----

  	-if exist Xfind rd /s /q Xfind

  	-if exist viminfo del viminfo

  	-del test.log

+ 	-if exists benchmark.out del benchmark.out

  .in.out:

  	-if exist $*.failed del $*.failed

***************

*** 103,105 ****

--- 104,114 ----

  nolog:

  	-del test.log

+ 

+ benchmark:

+ 	bench_re_freeze.out

+ 

+ bench_re_freeze.out: bench_re_freeze.vim

+ 	-if exist benchmark.out del benchmark.out

+ 	$(VIMPROG) -u dos.vim -U NONE --noplugin $*.in

+ 	@IF EXIST benchmark.out ( type benchmark.out )

*** ../vim-7.4.496/src/testdir/Make_ming.mak	2014-10-21 20:57:11.534295006 +0200

--- src/testdir/Make_ming.mak	2014-11-05 14:15:09.608774776 +0100

***************

*** 12,22 ****

--- 12,24 ----

  DEL = rm -f

  MV = mv

  CP = cp

+ CAT = cat

  DIRSLASH = /

  else

  DEL = del

  MV = rename

  CP = copy

+ CAT = type

  DIRSLASH = \\

  endif

***************

*** 72,77 ****

--- 74,81 ----

  SCRIPTS_GUI = test16.out

+ SCRIPTS_BENCH = bench_re_freeze.out

+ 

  .SUFFIXES: .in .out

  vimall:	fixff $(SCRIPTS16) $(SCRIPTS) $(SCRIPTS_GUI) $(SCRIPTS32)

***************

*** 80,85 ****

--- 84,91 ----

  nongui:	fixff $(SCRIPTS16) $(SCRIPTS)

  	echo ALL DONE

+ benchmark: $(SCRIPTS_BENCH)

+ 

  small:

  	echo ALL DONE

***************

*** 114,116 ****

--- 120,127 ----

  	-$(DEL) X*

  	-$(DEL) test.ok

  	-$(DEL) viminfo

+ 

+ bench_re_freeze.out: bench_re_freeze.vim

+ 	-$(DEL) benchmark.out

+ 	$(VIMPROG) -u dos.vim -U NONE --noplugin $*.in

+ 	$(CAT) benchmark.out

*** ../vim-7.4.496/src/testdir/Make_os2.mak	2014-10-21 20:57:11.538295006 +0200

--- src/testdir/Make_os2.mak	2014-11-05 12:57:59.616886342 +0100

***************

*** 50,55 ****

--- 50,57 ----

  		test_signs.out \

  		test_utf8.out

+ SCRIPTS_BENCH = bench_re_freeze.out

+ 

  .SUFFIXES: .in .out

  all:	/tmp $(SCRIPTS)

***************

*** 57,62 ****

--- 59,66 ----

  $(SCRIPTS): $(VIMPROG)

+ benchmark: $(SCRIPTS_BENCH)

+ 

  clean:

  	-rm -rf *.out Xdotest test.ok tiny.vim small.vim mbyte.vim viminfo

***************

*** 75,77 ****

--- 79,88 ----

  # Create a directory for temp files

  /tmp:

  	-mkdir /tmp

+ 

+ bench_re_freeze.out: bench_re_freeze.vim

+ 	-del $*.failed test.ok benchmark.out

+ 	copy $*.ok test.ok

+ 	$(VIMPROG) -u os2.vim --noplugin -s dotest.in $*.in