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Overview
| Comment: | Suppress excess OP_Null opcodes caused by binary IS or IS NOT operators that are converted into unary ISNULL or NOTNULL operators. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
cff1b36ab2c417611f59e96694005c03 |
| User & Date: | drh 2009-11-12 03:46:34.000 |
Context
|
2009-11-12
| ||
| 04:26 | Suppress unnecessary OP_Noop instructions on when the right table of a LEFT JOIN uses the index-only optimization. (check-in: e8aec08bee user: drh tags: trunk) | |
| 03:46 | Suppress excess OP_Null opcodes caused by binary IS or IS NOT operators that are converted into unary ISNULL or NOTNULL operators. (check-in: cff1b36ab2 user: drh tags: trunk) | |
| 03:13 | Adjustments to the implementation of LIMIT so that it uses fewer opcodes. (check-in: 39d5b292d2 user: drh tags: trunk) | |
Changes
Changes to src/parse.y.
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pOut->zStart = pOperand->zStart;
pOut->zEnd = &pPostOp->z[pPostOp->n];
}
}
expr(A) ::= expr(X) ISNULL|NOTNULL(E). {spanUnaryPostfix(&A,pParse,@E,&X,&E);}
expr(A) ::= expr(X) NOT NULL(E). {spanUnaryPostfix(&A,pParse,TK_NOTNULL,&X,&E);}
// expr1 IS expr2
// expr1 IS NOT expr2
//
// If expr2 is NULL then code as TK_ISNULL or TK_NOTNULL. If expr2
// is any other expression, code as TK_IS or TK_ISNOT.
//
expr(A) ::= expr(X) IS expr(Y). {
spanBinaryExpr(&A,pParse,TK_IS,&X,&Y);
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pOut->zStart = pOperand->zStart;
pOut->zEnd = &pPostOp->z[pPostOp->n];
}
}
expr(A) ::= expr(X) ISNULL|NOTNULL(E). {spanUnaryPostfix(&A,pParse,@E,&X,&E);}
expr(A) ::= expr(X) NOT NULL(E). {spanUnaryPostfix(&A,pParse,TK_NOTNULL,&X,&E);}
%include {
/* A routine to convert a binary TK_IS or TK_ISNOT expression into a
** unary TK_ISNULL or TK_NOTNULL expression. */
static void binaryToUnaryIfNull(Parse *pParse, Expr *pY, Expr *pA, int op){
sqlite3 *db = pParse->db;
if( db->mallocFailed==0 && pY->op==TK_NULL ){
pA->op = op;
sqlite3ExprDelete(db, pA->pRight);
pA->pRight = 0;
}
}
}
// expr1 IS expr2
// expr1 IS NOT expr2
//
// If expr2 is NULL then code as TK_ISNULL or TK_NOTNULL. If expr2
// is any other expression, code as TK_IS or TK_ISNOT.
//
expr(A) ::= expr(X) IS expr(Y). {
spanBinaryExpr(&A,pParse,TK_IS,&X,&Y);
binaryToUnaryIfNull(pParse, Y.pExpr, A.pExpr, TK_ISNULL);
}
expr(A) ::= expr(X) IS NOT expr(Y). {
spanBinaryExpr(&A,pParse,TK_ISNOT,&X,&Y);
binaryToUnaryIfNull(pParse, Y.pExpr, A.pExpr, TK_NOTNULL);
}
%include {
/* Construct an expression node for a unary prefix operator
*/
static void spanUnaryPrefix(
ExprSpan *pOut, /* Write the new expression node here */
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