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Reuse registers better in the inner loop of a SELECT statement. (CVS 4719)

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FossilOrigin-Name: 5ba4e5adf638c6812a2813961ea30a11a670409c
This commit is contained in:
drh
2008-01-17 17:15:56 +00:00
parent 9cbf3425fb
commit d847eaad91
4 changed files with 40 additions and 35 deletions
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55
src/select.c
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@@ -12,7 +12,7 @@
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.404 2008/01/17 16:22:15 drh Exp $
** $Id: select.c,v 1.405 2008/01/17 17:15:56 drh Exp $
*/
#include "sqliteInt.h"
@@ -516,11 +516,13 @@ static int selectInnerLoop(
char *aff /* affinity string if eDest is SRT_Union */
){
Vdbe *v = pParse->pVdbe;
int i, n;
int i;
int hasDistinct; /* True if the DISTINCT keyword is present */
int iMem; /* Start of memory holding result set */
int eDest = pDest->eDest;
int iParm = pDest->iParm;
int regResult; /* Start of memory holding result set */
int eDest = pDest->eDest; /* How to dispose of results */
int iParm = pDest->iParm; /* First argument to disposal method */
int nResultCol; /* Number of result columns */
int nToFree; /* Number of result columns to release */
if( v==0 ) return 0;
assert( pEList!=0 );
@@ -536,29 +538,30 @@ static int selectInnerLoop(
/* Pull the requested columns.
*/
if( nColumn>0 ){
n = nColumn;
nResultCol = nColumn;
}else{
n = pEList->nExpr;
nResultCol = pEList->nExpr;
}
if( pDest->iMem>0 ){
iMem = pDest->iMem;
regResult = pDest->iMem;
nToFree = 0;
}else{
pDest->iMem = iMem = pParse->nMem+1;
pParse->nMem += n;
pDest->iMem = regResult = sqlite3GetTempRange(pParse, nResultCol);
nToFree = nResultCol;
}
if( nColumn>0 ){
for(i=0; i<nColumn; i++){
sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, iMem+i);
sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
}
}else if( eDest!=SRT_Exists ){
/* If the destination is an EXISTS(...) expression, the actual
** values returned by the SELECT are not required.
*/
for(i=0; i<n; i++){
sqlite3ExprCode(pParse, pEList->a[i].pExpr, iMem+i);
for(i=0; i<nResultCol; i++){
sqlite3ExprCode(pParse, pEList->a[i].pExpr, regResult+i);
}
}
nColumn = n;
nColumn = nResultCol;
/* If the DISTINCT keyword was present on the SELECT statement
** and this row has been seen before, then do not make this row
@@ -567,7 +570,7 @@ static int selectInnerLoop(
if( hasDistinct ){
assert( pEList!=0 );
assert( pEList->nExpr==nColumn );
codeDistinct(pParse, distinct, iContinue, nColumn, iMem);
codeDistinct(pParse, distinct, iContinue, nColumn, regResult);
if( pOrderBy==0 ){
codeOffset(v, p, iContinue);
}
@@ -585,7 +588,7 @@ static int selectInnerLoop(
case SRT_Union: {
int r1;
r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, nColumn, r1);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
if( aff ){
sqlite3VdbeChangeP4(v, -1, aff, P4_STATIC);
}
@@ -601,7 +604,7 @@ static int selectInnerLoop(
case SRT_Except: {
int addr, r1;
r1 = sqlite3GetTempReg(pParse);
addr = sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, nColumn, r1);
addr = sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
sqlite3VdbeChangeP4(v, -1, aff, P4_STATIC);
sqlite3VdbeAddOp3(v, OP_NotFound, iParm, addr+3, r1);
sqlite3VdbeAddOp1(v, OP_Delete, iParm);
@@ -615,7 +618,7 @@ static int selectInnerLoop(
case SRT_Table:
case SRT_EphemTab: {
int r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, nColumn, r1);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
if( pOrderBy ){
pushOntoSorter(pParse, pOrderBy, p, r1);
}else{
@@ -638,17 +641,17 @@ static int selectInnerLoop(
int addr2;
assert( nColumn==1 );
addr2 = sqlite3VdbeAddOp2(v, OP_IsNull, iMem, 0);
addr2 = sqlite3VdbeAddOp1(v, OP_IsNull, regResult);
p->affinity = sqlite3CompareAffinity(pEList->a[0].pExpr, pDest->affinity);
if( pOrderBy ){
/* At first glance you would think we could optimize out the
** ORDER BY in this case since the order of entries in the set
** does not matter. But there might be a LIMIT clause, in which
** case the order does matter */
pushOntoSorter(pParse, pOrderBy, p, iMem);
pushOntoSorter(pParse, pOrderBy, p, regResult);
}else{
int r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp4(v, OP_MakeRecord, iMem, 1, r1, &p->affinity, 1);
sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult, 1, r1, &p->affinity, 1);
sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
sqlite3ReleaseTempReg(pParse, r1);
}
@@ -671,9 +674,9 @@ static int selectInnerLoop(
case SRT_Mem: {
assert( nColumn==1 );
if( pOrderBy ){
pushOntoSorter(pParse, pOrderBy, p, iMem);
pushOntoSorter(pParse, pOrderBy, p, regResult);
}else{
sqlite3VdbeAddOp2(v, OP_Move, iMem, iParm);
sqlite3VdbeAddOp2(v, OP_Move, regResult, iParm);
/* The LIMIT clause will jump out of the loop for us */
}
break;
@@ -688,13 +691,14 @@ static int selectInnerLoop(
case SRT_Callback: {
if( pOrderBy ){
int r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, nColumn, r1);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
pushOntoSorter(pParse, pOrderBy, p, r1);
sqlite3ReleaseTempReg(pParse, r1);
}else if( eDest==SRT_Subroutine ){
nToFree = 0; /* Preserve registers. Subroutine will need them. */
sqlite3VdbeAddOp2(v, OP_Gosub, 0, iParm);
}else{
sqlite3VdbeAddOp2(v, OP_ResultRow, iMem, nColumn);
sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nColumn);
}
break;
}
@@ -718,6 +722,7 @@ static int selectInnerLoop(
sqlite3VdbeAddOp2(v, OP_AddImm, p->iLimit, -1);
sqlite3VdbeAddOp2(v, OP_IfZero, p->iLimit, iBreak);
}
sqlite3ReleaseTempRange(pParse, regResult, nToFree);
return 0;
}