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Avoid storing the result register for EXISTS and SELECT in any field of

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the Expr object - simply return the register number as the return value
of the function that codes those expressions.

FossilOrigin-Name: 7253f8fad1efe6b88666f0f8740d247ff07a7640
This commit is contained in:
drh
2009-10-30 13:25:56 +00:00
parent e05c929b78
commit 1450bc6e52
4 changed files with 26 additions and 21 deletions
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23
src/expr.c
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@@ -1372,6 +1372,8 @@ int sqlite3FindInIndex(Parse *pParse, Expr *pX, int *prNotFound){
int iTab = pParse->nTab++; /* Cursor of the RHS table */
int mustBeUnique = (prNotFound==0); /* True if RHS must be unique */
assert( pX->op==TK_IN );
/* Check to see if an existing table or index can be used to
** satisfy the query. This is preferable to generating a new
** ephemeral table.
@@ -1449,7 +1451,7 @@ int sqlite3FindInIndex(Parse *pParse, Expr *pX, int *prNotFound){
}
if( eType==0 ){
/* Could not found an existing able or index to use as the RHS b-tree.
/* Could not found an existing table or index to use as the RHS b-tree.
** We will have to generate an ephemeral table to do the job.
*/
int rMayHaveNull = 0;
@@ -1496,17 +1498,21 @@ int sqlite3FindInIndex(Parse *pParse, Expr *pX, int *prNotFound){
** If rMayHaveNull is zero, that means that the subquery is being used
** for membership testing only. There is no need to initialize any
** registers to indicate the presense or absence of NULLs on the RHS.
**
** For a SELECT or EXISTS operator, return the register that holds the
** result. For IN operators or if an error occurs, the return value is 0.
*/
#ifndef SQLITE_OMIT_SUBQUERY
void sqlite3CodeSubselect(
int sqlite3CodeSubselect(
Parse *pParse, /* Parsing context */
Expr *pExpr, /* The IN, SELECT, or EXISTS operator */
int rMayHaveNull, /* Register that records whether NULLs exist in RHS */
int isRowid /* If true, LHS of IN operator is a rowid */
){
int testAddr = 0; /* One-time test address */
int rReg = 0; /* Register storing resulting */
Vdbe *v = sqlite3GetVdbe(pParse);
if( NEVER(v==0) ) return;
if( NEVER(v==0) ) return 0;
sqlite3ExprCachePush(pParse);
/* This code must be run in its entirety every time it is encountered
@@ -1571,7 +1577,7 @@ void sqlite3CodeSubselect(
dest.affinity = (u8)affinity;
assert( (pExpr->iTable&0x0000FFFF)==pExpr->iTable );
if( sqlite3Select(pParse, pExpr->x.pSelect, &dest) ){
return;
return 0;
}
pEList = pExpr->x.pSelect->pEList;
if( ALWAYS(pEList!=0 && pEList->nExpr>0) ){
@@ -1671,9 +1677,9 @@ void sqlite3CodeSubselect(
sqlite3ExprDelete(pParse->db, pSel->pLimit);
pSel->pLimit = sqlite3PExpr(pParse, TK_INTEGER, 0, 0, &one);
if( sqlite3Select(pParse, pSel, &dest) ){
return;
return 0;
}
pExpr->iColumn = (i16)dest.iParm;
rReg = dest.iParm;
ExprSetIrreducible(pExpr);
break;
}
@@ -1684,7 +1690,7 @@ void sqlite3CodeSubselect(
}
sqlite3ExprCachePop(pParse, 1);
return;
return rReg;
}
#endif /* SQLITE_OMIT_SUBQUERY */
@@ -2441,8 +2447,7 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
case TK_SELECT: {
testcase( op==TK_EXISTS );
testcase( op==TK_SELECT );
sqlite3CodeSubselect(pParse, pExpr, 0, 0);
inReg = pExpr->iColumn;
inReg = sqlite3CodeSubselect(pParse, pExpr, 0, 0);
break;
}
case TK_IN: {