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Overview
| Comment: | In the lemon-generated parser, store the number of symbols on the RHS of each rule as a negative number and add it to the stack pointer, rather than storing the value as a positive and subtracting it. This makes the parser faster. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA3-256: | b362f0d8ed34839bf3b29d10ed0853ab |
| User & Date: | drh 2017-06-28 13:47:56 |
Context
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2017-06-28
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| 14:26 | Minor tweak to the SQL grammar to make the parser tables a few bytes smaller. check-in: cc4810b2 user: drh tags: trunk | |
| 13:47 | In the lemon-generated parser, store the number of symbols on the RHS of each rule as a negative number and add it to the stack pointer, rather than storing the value as a positive and subtracting it. This makes the parser faster. check-in: b362f0d8 user: drh tags: trunk | |
| 11:56 | In the lemon-generated parser, automatically promote SHIFTREDUCE actions on nonterminal systems to pure REDUCE actions, for a performance enhancement. check-in: c46d94a8 user: drh tags: trunk | |
Changes
Changes to tool/lemon.c.
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/* Generate the table of rule information
**
** Note: This code depends on the fact that rules are number
** sequentually beginning with 0.
*/
for(rp=lemp->rule; rp; rp=rp->next){
fprintf(out," { %d, %d },\n",rp->lhs->index,rp->nrhs); lineno++;
}
tplt_xfer(lemp->name,in,out,&lineno);
/* Generate code which execution during each REDUCE action */
i = 0;
for(rp=lemp->rule; rp; rp=rp->next){
i += translate_code(lemp, rp);
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| |
4418 4419 4420 4421 4422 4423 4424 4425 4426 4427 4428 4429 4430 4431 4432 |
/* Generate the table of rule information
**
** Note: This code depends on the fact that rules are number
** sequentually beginning with 0.
*/
for(rp=lemp->rule; rp; rp=rp->next){
fprintf(out," { %d, %d },\n",rp->lhs->index,-rp->nrhs); lineno++;
}
tplt_xfer(lemp->name,in,out,&lineno);
/* Generate code which execution during each REDUCE action */
i = 0;
for(rp=lemp->rule; rp; rp=rp->next){
i += translate_code(lemp, rp);
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Changes to tool/lempar.c.
631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 ... 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 ... 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 |
yyTraceShift(yypParser, yyNewState);
}
/* The following table contains information about every rule that
** is used during the reduce.
*/
static const struct {
YYCODETYPE lhs; /* Symbol on the left-hand side of the rule */
unsigned char nrhs; /* Number of right-hand side symbols in the rule */
} yyRuleInfo[] = {
%%
};
static void yy_accept(yyParser*); /* Forward Declaration */
/*
................................................................................
int yysize; /* Amount to pop the stack */
ParseARG_FETCH;
yymsp = yypParser->yytos;
#ifndef NDEBUG
if( yyTraceFILE && yyruleno<(int)(sizeof(yyRuleName)/sizeof(yyRuleName[0])) ){
yysize = yyRuleInfo[yyruleno].nrhs;
fprintf(yyTraceFILE, "%sReduce [%s], go to state %d.\n", yyTracePrompt,
yyRuleName[yyruleno], yymsp[-yysize].stateno);
}
#endif /* NDEBUG */
/* Check that the stack is large enough to grow by a single entry
** if the RHS of the rule is empty. This ensures that there is room
** enough on the stack to push the LHS value */
if( yyRuleInfo[yyruleno].nrhs==0 ){
................................................................................
/********** Begin reduce actions **********************************************/
%%
/********** End reduce actions ************************************************/
};
assert( yyruleno<sizeof(yyRuleInfo)/sizeof(yyRuleInfo[0]) );
yygoto = yyRuleInfo[yyruleno].lhs;
yysize = yyRuleInfo[yyruleno].nrhs;
yyact = yy_find_reduce_action(yymsp[-yysize].stateno,(YYCODETYPE)yygoto);
/* There are no SHIFTREDUCE actions on nonterminals because the table
** generator has simplified them to pure REDUCE actions. */
assert( !(yyact>YY_MAX_SHIFT && yyact<=YY_MAX_SHIFTREDUCE) );
/* It is not possible for a REDUCE to be followed by an error */
assert( yyact!=YY_ERROR_ACTION );
if( yyact==YY_ACCEPT_ACTION ){
yypParser->yytos -= yysize;
yy_accept(yypParser);
}else{
yymsp -= yysize-1;
yypParser->yytos = yymsp;
yymsp->stateno = (YYACTIONTYPE)yyact;
yymsp->major = (YYCODETYPE)yygoto;
yyTraceShift(yypParser, yyact);
}
}
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631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 ... 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 ... 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 |
yyTraceShift(yypParser, yyNewState);
}
/* The following table contains information about every rule that
** is used during the reduce.
*/
static const struct {
YYCODETYPE lhs; /* Symbol on the left-hand side of the rule */
signed char nrhs; /* Negative of the number of RHS symbols in the rule */
} yyRuleInfo[] = {
%%
};
static void yy_accept(yyParser*); /* Forward Declaration */
/*
................................................................................
int yysize; /* Amount to pop the stack */
ParseARG_FETCH;
yymsp = yypParser->yytos;
#ifndef NDEBUG
if( yyTraceFILE && yyruleno<(int)(sizeof(yyRuleName)/sizeof(yyRuleName[0])) ){
yysize = yyRuleInfo[yyruleno].nrhs;
fprintf(yyTraceFILE, "%sReduce [%s], go to state %d.\n", yyTracePrompt,
yyRuleName[yyruleno], yymsp[yysize].stateno);
}
#endif /* NDEBUG */
/* Check that the stack is large enough to grow by a single entry
** if the RHS of the rule is empty. This ensures that there is room
** enough on the stack to push the LHS value */
if( yyRuleInfo[yyruleno].nrhs==0 ){
................................................................................
/********** Begin reduce actions **********************************************/
%%
/********** End reduce actions ************************************************/
};
assert( yyruleno<sizeof(yyRuleInfo)/sizeof(yyRuleInfo[0]) );
yygoto = yyRuleInfo[yyruleno].lhs;
yysize = yyRuleInfo[yyruleno].nrhs;
yyact = yy_find_reduce_action(yymsp[yysize].stateno,(YYCODETYPE)yygoto);
/* There are no SHIFTREDUCE actions on nonterminals because the table
** generator has simplified them to pure REDUCE actions. */
assert( !(yyact>YY_MAX_SHIFT && yyact<=YY_MAX_SHIFTREDUCE) );
/* It is not possible for a REDUCE to be followed by an error */
assert( yyact!=YY_ERROR_ACTION );
if( yyact==YY_ACCEPT_ACTION ){
yypParser->yytos += yysize;
yy_accept(yypParser);
}else{
yymsp += yysize+1;
yypParser->yytos = yymsp;
yymsp->stateno = (YYACTIONTYPE)yyact;
yymsp->major = (YYCODETYPE)yygoto;
yyTraceShift(yypParser, yyact);
}
}
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