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Overview
Comment:Improvements to the initialization of the push-down automoton for the Lemon-generated parser. Smaller and faster.
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SHA1:3b28b68e232060f8b2fe2fe6fa478280da2006ff
User & Date: drh 2016-05-24 00:40:54
Context
2016-05-24
16:20
Fix an obscure problem with transactions written in "PRAGMA synchronous=full" mode on systems that do not support POWERSAFE_OVERWRITE causing an xSync() call to be omitted if the last frame written by a transaction is aligned to a sector boundary. This means that if a power failure or OS crash occurs very soon after such a transaction is committed, it may be lost following system recovery. check-in: 37de3eab user: dan tags: trunk
00:40
Improvements to the initialization of the push-down automoton for the Lemon-generated parser. Smaller and faster. check-in: 3b28b68e user: drh tags: trunk
2016-05-23
21:56
Use a pointer to the top of the stack rather than an index into the stack in the Lemon-generated parser template, for about 6.6% parser performance gain. check-in: 3c2a7705 user: drh tags: trunk
Changes
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Changes to tool/lempar.c.

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#if YYSTACKDEPTH<=0
/*
** Try to increase the size of the parser stack.
*/
static void yyGrowStack(yyParser *p){
  int newSize;

  yyStackEntry *pNew;

  newSize = p->yystksz*2 + 100;

  pNew = realloc(p->yystack, newSize*sizeof(pNew[0]));
  if( pNew ){
    p->yystack = pNew;

    p->yystksz = newSize;
#ifndef NDEBUG
    if( yyTraceFILE ){
      fprintf(yyTraceFILE,"%sStack grows to %d entries!\n",
              yyTracePrompt, p->yystksz);
    }
#endif
................................................................................
** A pointer to a parser.  This pointer is used in subsequent calls
** to Parse and ParseFree.
*/
void *ParseAlloc(void *(*mallocProc)(YYMALLOCARGTYPE)){
  yyParser *pParser;
  pParser = (yyParser*)(*mallocProc)( (YYMALLOCARGTYPE)sizeof(yyParser) );
  if( pParser ){
    pParser->yytos = 0;
#ifdef YYTRACKMAXSTACKDEPTH
    pParser->yyhwm = 0;
#endif
#if YYSTACKDEPTH<=0

    pParser->yystack = NULL;
    pParser->yystksz = 0;
    yyGrowStack(pParser);
#endif



  }
  return pParser;
}

/* The following function deletes the "minor type" or semantic value
** associated with a symbol.  The symbol can be either a terminal
** or nonterminal. "yymajor" is the symbol code, and "yypminor" is
................................................................................
  void *p,                    /* The parser to be deleted */
  void (*freeProc)(void*)     /* Function used to reclaim memory */
){
  yyParser *pParser = (yyParser*)p;
#ifndef YYPARSEFREENEVERNULL
  if( pParser==0 ) return;
#endif
  while( pParser->yytos>=pParser->yystack ) yy_pop_parser_stack(pParser);
#if YYSTACKDEPTH<=0
  free(pParser->yystack);
#endif
  (*freeProc)((void*)pParser);
}

/*
................................................................................
   ParseARG_FETCH;
   yypParser->yytos--;
#ifndef NDEBUG
   if( yyTraceFILE ){
     fprintf(yyTraceFILE,"%sStack Overflow!\n",yyTracePrompt);
   }
#endif
   while( yypParser->yytos>=yypParser->yystack ) yy_pop_parser_stack(yypParser);
   /* Here code is inserted which will execute if the parser
   ** stack every overflows */
/******** Begin %stack_overflow code ******************************************/
%%
/******** End %stack_overflow code ********************************************/
   ParseARG_STORE; /* Suppress warning about unused %extra_argument var */
}
................................................................................
){
  ParseARG_FETCH;
#ifndef NDEBUG
  if( yyTraceFILE ){
    fprintf(yyTraceFILE,"%sFail!\n",yyTracePrompt);
  }
#endif
  while( yypParser->yytos>=yypParser->yystack ) yy_pop_parser_stack(yypParser);
  yypParser->yytos = 0;
  /* Here code is inserted which will be executed whenever the
  ** parser fails */
/************ Begin %parse_failure code ***************************************/
%%
/************ End %parse_failure code *****************************************/
  ParseARG_STORE; /* Suppress warning about unused %extra_argument variable */
}
................................................................................
){
  ParseARG_FETCH;
#ifndef NDEBUG
  if( yyTraceFILE ){
    fprintf(yyTraceFILE,"%sAccept!\n",yyTracePrompt);
  }
#endif
  while( yypParser->yytos>=yypParser->yystack ) yy_pop_parser_stack(yypParser);
  yypParser->yytos = 0;
  /* Here code is inserted which will be executed whenever the
  ** parser accepts */
/*********** Begin %parse_accept code *****************************************/
%%
/*********** End %parse_accept code *******************************************/
  ParseARG_STORE; /* Suppress warning about unused %extra_argument variable */
}
................................................................................
#ifdef YYERRORSYMBOL
  int yyerrorhit = 0;   /* True if yymajor has invoked an error */
#endif
  yyParser *yypParser;  /* The parser */

  /* (re)initialize the parser, if necessary */
  yypParser = (yyParser*)yyp;
  if( yypParser->yytos==0 ){
#if YYSTACKDEPTH<=0
    if( yypParser->yystksz <=0 ){
      yyStackOverflow(yypParser);
      return;
    }
#endif
    yypParser->yytos = yypParser->yystack;
#ifndef YYNOERRORRECOVERY
    yypParser->yyerrcnt = -1;
#endif
    yypParser->yystack[0].stateno = 0;
    yypParser->yystack[0].major = 0;
#ifndef NDEBUG
    if( yyTraceFILE ){
      fprintf(yyTraceFILE,"%sInitialize. Empty stack. State 0\n",
              yyTracePrompt);
    }
#endif
  }
#if !defined(YYERRORSYMBOL) && !defined(YYNOERRORRECOVERY)
  yyendofinput = (yymajor==0);
#endif
  ParseARG_STORE;

#ifndef NDEBUG
  if( yyTraceFILE ){
................................................................................
      yy_destructor(yypParser,(YYCODETYPE)yymajor,&yyminorunion);
      if( yyendofinput ){
        yy_parse_failed(yypParser);
      }
      yymajor = YYNOCODE;
#endif
    }
  }while( yymajor!=YYNOCODE && yypParser->yytos>=yypParser->yystack );
#ifndef NDEBUG
  if( yyTraceFILE ){
    yyStackEntry *i;
    char cDiv = '[';
    fprintf(yyTraceFILE,"%sReturn. Stack=",yyTracePrompt);
    for(i=&yypParser->yystack[1]; i<=yypParser->yytos; i++){
      fprintf(yyTraceFILE,"%c%s", cDiv, yyTokenName[i->major]);







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#if YYSTACKDEPTH<=0
/*
** Try to increase the size of the parser stack.
*/
static void yyGrowStack(yyParser *p){
  int newSize;
  int idx;
  yyStackEntry *pNew;

  newSize = p->yystksz*2 + 100;
  idx = p->yytos ? (int)(p->yytos - p->yystack) : 0;
  pNew = realloc(p->yystack, newSize*sizeof(pNew[0]));
  if( pNew ){
    p->yystack = pNew;
    p->yytos = &p->yystack[idx];
    p->yystksz = newSize;
#ifndef NDEBUG
    if( yyTraceFILE ){
      fprintf(yyTraceFILE,"%sStack grows to %d entries!\n",
              yyTracePrompt, p->yystksz);
    }
#endif
................................................................................
** A pointer to a parser.  This pointer is used in subsequent calls
** to Parse and ParseFree.
*/
void *ParseAlloc(void *(*mallocProc)(YYMALLOCARGTYPE)){
  yyParser *pParser;
  pParser = (yyParser*)(*mallocProc)( (YYMALLOCARGTYPE)sizeof(yyParser) );
  if( pParser ){

#ifdef YYTRACKMAXSTACKDEPTH
    pParser->yyhwm = 0;
#endif
#if YYSTACKDEPTH<=0
    pParser->yytos = NULL;
    pParser->yystack = NULL;
    pParser->yystksz = 0;
    yyGrowStack(pParser);
#endif
    pParser->yytos = pParser->yystack;
    pParser->yystack[0].stateno = 0;
    pParser->yystack[0].major = 0;
  }
  return pParser;
}

/* The following function deletes the "minor type" or semantic value
** associated with a symbol.  The symbol can be either a terminal
** or nonterminal. "yymajor" is the symbol code, and "yypminor" is
................................................................................
  void *p,                    /* The parser to be deleted */
  void (*freeProc)(void*)     /* Function used to reclaim memory */
){
  yyParser *pParser = (yyParser*)p;
#ifndef YYPARSEFREENEVERNULL
  if( pParser==0 ) return;
#endif
  while( pParser->yytos>pParser->yystack ) yy_pop_parser_stack(pParser);
#if YYSTACKDEPTH<=0
  free(pParser->yystack);
#endif
  (*freeProc)((void*)pParser);
}

/*
................................................................................
   ParseARG_FETCH;
   yypParser->yytos--;
#ifndef NDEBUG
   if( yyTraceFILE ){
     fprintf(yyTraceFILE,"%sStack Overflow!\n",yyTracePrompt);
   }
#endif
   while( yypParser->yytos>yypParser->yystack ) yy_pop_parser_stack(yypParser);
   /* Here code is inserted which will execute if the parser
   ** stack every overflows */
/******** Begin %stack_overflow code ******************************************/
%%
/******** End %stack_overflow code ********************************************/
   ParseARG_STORE; /* Suppress warning about unused %extra_argument var */
}
................................................................................
){
  ParseARG_FETCH;
#ifndef NDEBUG
  if( yyTraceFILE ){
    fprintf(yyTraceFILE,"%sFail!\n",yyTracePrompt);
  }
#endif
  while( yypParser->yytos>yypParser->yystack ) yy_pop_parser_stack(yypParser);

  /* Here code is inserted which will be executed whenever the
  ** parser fails */
/************ Begin %parse_failure code ***************************************/
%%
/************ End %parse_failure code *****************************************/
  ParseARG_STORE; /* Suppress warning about unused %extra_argument variable */
}
................................................................................
){
  ParseARG_FETCH;
#ifndef NDEBUG
  if( yyTraceFILE ){
    fprintf(yyTraceFILE,"%sAccept!\n",yyTracePrompt);
  }
#endif
  while( yypParser->yytos>yypParser->yystack ) yy_pop_parser_stack(yypParser);

  /* Here code is inserted which will be executed whenever the
  ** parser accepts */
/*********** Begin %parse_accept code *****************************************/
%%
/*********** End %parse_accept code *******************************************/
  ParseARG_STORE; /* Suppress warning about unused %extra_argument variable */
}
................................................................................
#ifdef YYERRORSYMBOL
  int yyerrorhit = 0;   /* True if yymajor has invoked an error */
#endif
  yyParser *yypParser;  /* The parser */

  /* (re)initialize the parser, if necessary */
  yypParser = (yyParser*)yyp;
  assert( yypParser->yytos!=0 );



















#if !defined(YYERRORSYMBOL) && !defined(YYNOERRORRECOVERY)
  yyendofinput = (yymajor==0);
#endif
  ParseARG_STORE;

#ifndef NDEBUG
  if( yyTraceFILE ){
................................................................................
      yy_destructor(yypParser,(YYCODETYPE)yymajor,&yyminorunion);
      if( yyendofinput ){
        yy_parse_failed(yypParser);
      }
      yymajor = YYNOCODE;
#endif
    }
  }while( yymajor!=YYNOCODE && yypParser->yytos>yypParser->yystack );
#ifndef NDEBUG
  if( yyTraceFILE ){
    yyStackEntry *i;
    char cDiv = '[';
    fprintf(yyTraceFILE,"%sReturn. Stack=",yyTracePrompt);
    for(i=&yypParser->yystack[1]; i<=yypParser->yytos; i++){
      fprintf(yyTraceFILE,"%c%s", cDiv, yyTokenName[i->major]);