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Avoid duplicate OP_Column opcodes by remembering prior results.

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This is similar to CSE, but only applies to columns. (CVS 4943)

FossilOrigin-Name: c29ee0fed23dcdbd9dde6b1e42b603100ea2389c
This commit is contained in:
drh
2008-03-31 23:48:03 +00:00
parent 678ccce8b3
commit e55cbd7228
9 changed files with 209 additions and 47 deletions
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159
src/expr.c
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@@ -12,7 +12,7 @@
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.358 2008/03/31 18:19:54 drh Exp $
** $Id: expr.c,v 1.359 2008/03/31 23:48:04 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -1779,8 +1779,11 @@ void sqlite3CodeSubselect(Parse *pParse, Expr *pExpr){
}
/* Evaluate the expression and insert it into the temp table */
pParse->disableColCache++;
sqlite3ExprCode(pParse, pE2, r1);
pParse->disableColCache--;
sqlite3VdbeAddOp4(v, OP_MakeRecord, r1, 1, r2, &affinity, 1);
sqlite3ExprExpireColumnCacheLines(pParse, r1, r1);
sqlite3VdbeAddOp2(v, OP_IdxInsert, pExpr->iTable, r2);
}
sqlite3ReleaseTempReg(pParse, r1);
@@ -1894,17 +1897,35 @@ static void codeInteger(Vdbe *v, const char *z, int n, int negFlag, int iMem){
/*
** Generate code that will extract the iColumn-th column from
** table pTab and store the column value in register iReg.
** There is an open cursor to pTab in
** iTable. If iColumn<0 then code is generated that extracts the rowid.
** table pTab and store the column value in a register. An effort
** is made to store the column value in register iReg, but this is
** not guaranteed. The location of the column value is returned.
**
** There must be an open cursor to pTab in iTable when this routine
** is called. If iColumn<0 then code is generated that extracts the rowid.
*/
void sqlite3ExprCodeGetColumn(
Vdbe *v, /* The VM being created */
int sqlite3ExprCodeGetColumn(
Parse *pParse, /* Parsing and code generating context */
Table *pTab, /* Description of the table we are reading from */
int iColumn, /* Index of the table column */
int iTable, /* The cursor pointing to the table */
int iReg /* Store results here */
){
Vdbe *v = pParse->pVdbe;
int i;
for(i=0; i<pParse->nColCache; i++){
if( pParse->aColCache[i].iTable==iTable
&& pParse->aColCache[i].iColumn==iColumn ){
#if 0
sqlite3VdbeAddOp0(v, OP_Noop);
VdbeComment((v, "OPT: tab%d.col%d -> r%d",
iTable, iColumn, pParse->aColCache[i].iReg));
#endif
return pParse->aColCache[i].iReg;
}
}
assert( v!=0 );
if( iColumn<0 ){
int op = (pTab && IsVirtual(pTab)) ? OP_VRowid : OP_Rowid;
sqlite3VdbeAddOp2(v, op, iTable, iReg);
@@ -1920,6 +1941,79 @@ void sqlite3ExprCodeGetColumn(
}
#endif
}
if( pParse->disableColCache==0 ){
i = pParse->iColCache;
pParse->aColCache[i].iTable = iTable;
pParse->aColCache[i].iColumn = iColumn;
pParse->aColCache[i].iReg = iReg;
i++;
if( i>ArraySize(pParse->aColCache) ) i = 0;
if( i>pParse->nColCache ) pParse->nColCache = i;
}
return iReg;
}
/*
** Disable (+1) or enable (-1) the adding of new column cache entries.
*/
void sqlite3ExprColumnCacheDisable(Parse *pParse, int disable){
assert( disable==-1 || disable==+1 );
assert( pParse->disableColCache>0 || disable==1 );
pParse->disableColCache += disable;
}
/*
** Clear all column cache entries associated with the vdbe
** cursor with cursor number iTable.
*/
void sqlite3ExprClearColumnCache(Parse *pParse, int iTable){
if( iTable<0 ){
pParse->nColCache = 0;
pParse->iColCache = 0;
}else{
int i;
for(i=0; i<pParse->nColCache; i++){
if( pParse->aColCache[i].iTable==iTable ){
pParse->aColCache[i] = pParse->aColCache[--pParse->nColCache];
}
}
pParse->iColCache = pParse->nColCache;
}
}
/*
** Expire all column cache entry associated with register between
** iFrom and iTo, inclusive. If there are no column cache entries
** on those registers then this routine is a no-op.
**
** Call this routine when register contents are overwritten to
** make sure the new register value is not used in place of the
** value that was overwritten.
*/
void sqlite3ExprExpireColumnCacheLines(Parse *pParse, int iFrom, int iTo){
int i;
for(i=0; i<pParse->nColCache; i++){
int r = pParse->aColCache[i].iReg;
if( r>=iFrom && r<=iTo ){
pParse->aColCache[i] = pParse->aColCache[--pParse->nColCache];
}
}
pParse->iColCache = pParse->nColCache;
}
/*
** Generate code to moves content from one register to another.
** Keep the column cache up-to-date.
*/
void sqlite3ExprCodeMove(Parse *pParse, int iFrom, int iTo){
int i;
if( iFrom==iTo ) return;
sqlite3VdbeAddOp2(pParse->pVdbe, OP_Move, iFrom, iTo);
for(i=0; i<pParse->nColCache; i++){
if( pParse->aColCache[i].iReg==iFrom ){
pParse->aColCache[i].iReg = iTo;
}
}
}
/*
@@ -1971,7 +2065,7 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
assert( pParse->ckBase>0 );
inReg = pExpr->iColumn + pParse->ckBase;
}else{
sqlite3ExprCodeGetColumn(v, pExpr->pTab,
inReg = sqlite3ExprCodeGetColumn(pParse, pExpr->pTab,
pExpr->iColumn, pExpr->iTable, target);
}
break;
@@ -2096,7 +2190,7 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
}else{
regFree1 = r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp2(v, OP_Integer, 0, r1);
r2 = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
r2 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree2);
sqlite3VdbeAddOp3(v, OP_Subtract, r2, r1, target);
}
inReg = target;
@@ -2193,6 +2287,7 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
if( nExpr ){
sqlite3ReleaseTempRange(pParse, r1, nExpr);
}
sqlite3ExprExpireColumnCacheLines(pParse, r1, r1+nExpr-1);
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
@@ -2236,6 +2331,7 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
}else{
r2 = regFree2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp4(v, OP_MakeRecord, r1, 1, r2, &affinity, 1);
sqlite3ExprExpireColumnCacheLines(pParse, r1, r1);
j5 = sqlite3VdbeAddOp3(v, OP_Found, pExpr->iTable, 0, r2);
}
sqlite3VdbeAddOp2(v, OP_AddImm, target, -1);
@@ -2321,6 +2417,7 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
aListelem = pEList->a;
nExpr = pEList->nExpr;
endLabel = sqlite3VdbeMakeLabel(v);
sqlite3ExprColumnCacheDisable(pParse, 1);
if( (pX = pExpr->pLeft)!=0 ){
cacheX = *pX;
cacheX.iTable = sqlite3ExprCodeTemp(pParse, pX, &regFree1);
@@ -2348,6 +2445,7 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
sqlite3VdbeAddOp2(v, OP_Null, 0, target);
}
sqlite3VdbeResolveLabel(v, endLabel);
sqlite3ExprColumnCacheDisable(pParse, -1);
break;
}
#ifndef SQLITE_OMIT_TRIGGER
@@ -2532,13 +2630,17 @@ void sqlite3ExprIfTrue(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
case TK_AND: {
int d2 = sqlite3VdbeMakeLabel(v);
sqlite3ExprIfFalse(pParse, pExpr->pLeft, d2,jumpIfNull^SQLITE_JUMPIFNULL);
pParse->disableColCache++;
sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
pParse->disableColCache--;
sqlite3VdbeResolveLabel(v, d2);
break;
}
case TK_OR: {
sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
pParse->disableColCache++;
sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
pParse->disableColCache--;
break;
}
case TK_NOT: {
@@ -2664,13 +2766,17 @@ void sqlite3ExprIfFalse(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
switch( pExpr->op ){
case TK_AND: {
sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
pParse->disableColCache++;
sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
pParse->disableColCache--;
break;
}
case TK_OR: {
int d2 = sqlite3VdbeMakeLabel(v);
sqlite3ExprIfTrue(pParse, pExpr->pLeft, d2, jumpIfNull^SQLITE_JUMPIFNULL);
pParse->disableColCache++;
sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
pParse->disableColCache--;
sqlite3VdbeResolveLabel(v, d2);
break;
}
@@ -2980,15 +3086,39 @@ void sqlite3ExprAnalyzeAggList(NameContext *pNC, ExprList *pList){
}
}
/*
** Return true if any register in the range iFrom..iTo (inclusive)
** is used as part of the column cache.
*/
static int usedAsColumnCache(Parse *pParse, int iFrom, int iTo){
int i;
for(i=0; i<pParse->nColCache; i++){
int r = pParse->aColCache[i].iReg;
if( r>=iFrom && r<=iTo ) return 1;
}
return 0;
}
/*
** Allocate or deallocate temporary use registers during code generation.
*/
int sqlite3GetTempReg(Parse *pParse){
if( pParse->nTempReg ){
return pParse->aTempReg[--pParse->nTempReg];
}else{
int i, r;
if( pParse->nTempReg==0 ){
return ++pParse->nMem;
}
for(i=0; i<pParse->nTempReg; i++){
r = pParse->aTempReg[i];
if( usedAsColumnCache(pParse, r, r) ) continue;
}
if( i>=pParse->nTempReg ){
return ++pParse->nMem;
}
while( i<pParse->nTempReg-1 ){
pParse->aTempReg[i] = pParse->aTempReg[i+1];
}
pParse->nTempReg--;
return r;
}
void sqlite3ReleaseTempReg(Parse *pParse, int iReg){
if( iReg && pParse->nTempReg<ArraySize(pParse->aTempReg) ){
@@ -3001,9 +3131,10 @@ void sqlite3ReleaseTempReg(Parse *pParse, int iReg){
** Allocate or deallocate a block of nReg consecutive registers
*/
int sqlite3GetTempRange(Parse *pParse, int nReg){
int i;
if( nReg<=pParse->nRangeReg ){
i = pParse->iRangeReg;
int i, n;
i = pParse->iRangeReg;
n = pParse->nRangeReg;
if( nReg<=n && !usedAsColumnCache(pParse, i, i+n-1) ){
pParse->iRangeReg += nReg;
pParse->nRangeReg -= nReg;
}else{