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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 |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA3-256: |
b362f0d8ed34839bf3b29d10ed0853ab |
| User & Date: | drh 2017-06-28 13:47:56.467 |
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: cc4810b23e 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: b362f0d8ed 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: c46d94a8cd user: drh tags: trunk) | |
Changes
Changes to tool/lemon.c.
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4418 4419 4420 4421 4422 4423 4424 |
/* 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){
| | | 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.
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631 632 633 634 635 636 637 |
yyTraceShift(yypParser, yyNewState);
}
/* The following table contains information about every rule that
** is used during the reduce.
*/
static const struct {
| | | | 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 |
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 */
/*
|
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657 658 659 660 661 662 663 |
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,
| | | 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 |
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 ){
|
| ︙ | ︙ | |||
703 704 705 706 707 708 709 | /********** Begin reduce actions **********************************************/ %% /********** End reduce actions ************************************************/ }; assert( yyruleno<sizeof(yyRuleInfo)/sizeof(yyRuleInfo[0]) ); yygoto = yyRuleInfo[yyruleno].lhs; yysize = yyRuleInfo[yyruleno].nrhs; | | | | | 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 |
/********** 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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