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Overview
| Comment: | Further improvements to parser speed by enlarging lookup tables to eliminate the need to do range checking on the index prior to lookup. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | lemon-optimization |
| Files: | files | file ages | folders |
| SHA3-256: |
47d3e091ae49eb7947af5abef9b5b96b |
| User & Date: | drh 2019-08-28 11:31:11 |
Context
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2019-08-28
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| 11:49 | Fix an unreachable branch in sqlite3ParserFallback() (Closed-Leaf check-in: e059178b47 user: drh tags: lemon-optimization) | |
| 11:31 | Further improvements to parser speed by enlarging lookup tables to eliminate the need to do range checking on the index prior to lookup. (check-in: 47d3e091ae user: drh tags: lemon-optimization) | |
| 02:09 | Increase the size of the yy_lookahead table so that it is never necessary to down bounds checking on the index. (check-in: bafd872398 user: drh tags: lemon-optimization) | |
Changes
Changes to tool/lemon.c.
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fprintf(out, "};\n"); lineno++;
tplt_xfer(lemp->name,in,out,&lineno);
/* Generate the table of fallback tokens.
*/
if( lemp->has_fallback ){
int mx = lemp->nterminal - 1;
while( mx>0 && lemp->symbols[mx]->fallback==0 ){ mx--; }
lemp->tablesize += (mx+1)*szCodeType;
for(i=0; i<=mx; i++){
struct symbol *p = lemp->symbols[i];
if( p->fallback==0 ){
fprintf(out, " 0, /* %10s => nothing */\n", p->name);
}else{
fprintf(out, " %3d, /* %10s => %s */\n", p->fallback->index,
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> > | |
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fprintf(out, "};\n"); lineno++;
tplt_xfer(lemp->name,in,out,&lineno);
/* Generate the table of fallback tokens.
*/
if( lemp->has_fallback ){
int mx = lemp->nterminal - 1;
/* 2019-08-28: Generate fallback entries for every token to avoid
** having to do a range check on the index */
/* while( mx>0 && lemp->symbols[mx]->fallback==0 ){ mx--; } */
lemp->tablesize += (mx+1)*szCodeType;
for(i=0; i<=mx; i++){
struct symbol *p = lemp->symbols[i];
if( p->fallback==0 ){
fprintf(out, " 0, /* %10s => nothing */\n", p->name);
}else{
fprintf(out, " %3d, /* %10s => %s */\n", p->fallback->index,
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Changes to tool/lempar.c.
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assert( iLookAhead!=YYNOCODE );
assert( iLookAhead < YYNTOKEN );
i += iLookAhead;
assert( i<(int)YY_NLOOKAHEAD );
if( yy_lookahead[i]!=iLookAhead ){
#ifdef YYFALLBACK
YYCODETYPE iFallback; /* Fallback token */
if( iLookAhead<sizeof(yyFallback)/sizeof(yyFallback[0])
&& (iFallback = yyFallback[iLookAhead])!=0 ){
#ifndef NDEBUG
if( yyTraceFILE ){
fprintf(yyTraceFILE, "%sFALLBACK %s => %s\n",
yyTracePrompt, yyTokenName[iLookAhead], yyTokenName[iFallback]);
}
#endif
assert( yyFallback[iFallback]==0 ); /* Fallback loop must terminate */
................................................................................
iLookAhead = iFallback;
continue;
}
#endif
#ifdef YYWILDCARD
{
int j = i - iLookAhead + YYWILDCARD;
if(
#if YY_SHIFT_MIN+YYWILDCARD<0
j>=0 &&
#endif
#if YY_SHIFT_MAX+YYWILDCARD>=YY_ACTTAB_COUNT
j<YY_ACTTAB_COUNT &&
#endif
j<(int)(sizeof(yy_lookahead)/sizeof(yy_lookahead[0])) &&
yy_lookahead[j]==YYWILDCARD && iLookAhead>0
){
#ifndef NDEBUG
if( yyTraceFILE ){
fprintf(yyTraceFILE, "%sWILDCARD %s => %s\n",
yyTracePrompt, yyTokenName[iLookAhead],
yyTokenName[YYWILDCARD]);
}
#endif /* NDEBUG */
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assert( iLookAhead!=YYNOCODE );
assert( iLookAhead < YYNTOKEN );
i += iLookAhead;
assert( i<(int)YY_NLOOKAHEAD );
if( yy_lookahead[i]!=iLookAhead ){
#ifdef YYFALLBACK
YYCODETYPE iFallback; /* Fallback token */
assert( iLookAhead<sizeof(yyFallback)/sizeof(yyFallback[0]) );
iFallback = yyFallback[iLookAhead];
if( iFallback!=0 ){
#ifndef NDEBUG
if( yyTraceFILE ){
fprintf(yyTraceFILE, "%sFALLBACK %s => %s\n",
yyTracePrompt, yyTokenName[iLookAhead], yyTokenName[iFallback]);
}
#endif
assert( yyFallback[iFallback]==0 ); /* Fallback loop must terminate */
................................................................................
iLookAhead = iFallback;
continue;
}
#endif
#ifdef YYWILDCARD
{
int j = i - iLookAhead + YYWILDCARD;
assert( j<(int)(sizeof(yy_lookahead)/sizeof(yy_lookahead[0])) );
if( yy_lookahead[j]==YYWILDCARD && iLookAhead>0 ){
#ifndef NDEBUG
if( yyTraceFILE ){
fprintf(yyTraceFILE, "%sWILDCARD %s => %s\n",
yyTracePrompt, yyTokenName[iLookAhead],
yyTokenName[YYWILDCARD]);
}
#endif /* NDEBUG */
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