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Improved optimization of the AND and OR operators.

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FossilOrigin-Name: 0fbd154eb419b57b9c064c1f47346835d6324388b966b73f8a0122de065f08b1
This commit is contained in:
drh
2019-04-19 17:26:19 +00:00
parent 65455fc682
commit 17180fca9d
4 changed files with 69 additions and 31 deletions
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81
src/expr.c
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@@ -1808,6 +1808,33 @@ int sqlite3ExprTruthValue(const Expr *pExpr){
return pExpr->u.zToken[4]==0;
}
/*
** If pExpr is an AND or OR expression, try to simplify it by eliminating
** terms that are always true or false. Return the simplified expression.
** Or return the original expression if no simplification is possible.
**
** Examples:
**
** (x<10) AND true => (x<10)
** (x<10) AND false => false
** (x<10) AND (y=22 OR false) => (x<10) AND (y=22)
** (x<10) AND (y=22 OR true) => (x<10)
** (y=22) OR true => true
*/
Expr *sqlite3ExprSimplifiedAndOr(Expr *pExpr){
assert( pExpr!=0 );
if( pExpr->op==TK_AND || pExpr->op==TK_OR ){
Expr *pRight = sqlite3ExprSimplifiedAndOr(pExpr->pRight);
Expr *pLeft = sqlite3ExprSimplifiedAndOr(pExpr->pLeft);
if( ExprAlwaysTrue(pLeft) || ExprAlwaysFalse(pRight) ){
pExpr = pExpr->op==TK_AND ? pRight : pLeft;
}else if( ExprAlwaysTrue(pRight) || ExprAlwaysFalse(pLeft) ){
pExpr = pExpr->op==TK_AND ? pLeft : pRight;
}
}
return pExpr;
}
/*
** These routines are Walker callbacks used to check expressions to
@@ -4399,18 +4426,23 @@ void sqlite3ExprIfTrue(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
if( NEVER(pExpr==0) ) return; /* No way this can happen */
op = pExpr->op;
switch( op ){
case TK_AND: {
int d2 = sqlite3VdbeMakeLabel(pParse);
testcase( jumpIfNull==0 );
sqlite3ExprIfFalse(pParse, pExpr->pLeft, d2,jumpIfNull^SQLITE_JUMPIFNULL);
sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
sqlite3VdbeResolveLabel(v, d2);
break;
}
case TK_AND:
case TK_OR: {
testcase( jumpIfNull==0 );
sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
Expr *pAlt = sqlite3ExprSimplifiedAndOr(pExpr);
if( pAlt!=pExpr ){
sqlite3ExprIfTrue(pParse, pAlt, dest, jumpIfNull);
}else if( op==TK_AND ){
int d2 = sqlite3VdbeMakeLabel(pParse);
testcase( jumpIfNull==0 );
sqlite3ExprIfFalse(pParse, pExpr->pLeft, d2,
jumpIfNull^SQLITE_JUMPIFNULL);
sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
sqlite3VdbeResolveLabel(v, d2);
}else{
testcase( jumpIfNull==0 );
sqlite3ExprIfTrue(pParse, pExpr->pLeft, dest, jumpIfNull);
sqlite3ExprIfTrue(pParse, pExpr->pRight, dest, jumpIfNull);
}
break;
}
case TK_NOT: {
@@ -4566,18 +4598,23 @@ void sqlite3ExprIfFalse(Parse *pParse, Expr *pExpr, int dest, int jumpIfNull){
assert( pExpr->op!=TK_GE || op==OP_Lt );
switch( pExpr->op ){
case TK_AND: {
testcase( jumpIfNull==0 );
sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
break;
}
case TK_AND:
case TK_OR: {
int d2 = sqlite3VdbeMakeLabel(pParse);
testcase( jumpIfNull==0 );
sqlite3ExprIfTrue(pParse, pExpr->pLeft, d2, jumpIfNull^SQLITE_JUMPIFNULL);
sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
sqlite3VdbeResolveLabel(v, d2);
Expr *pAlt = sqlite3ExprSimplifiedAndOr(pExpr);
if( pAlt!=pExpr ){
sqlite3ExprIfFalse(pParse, pAlt, dest, jumpIfNull);
}else if( pExpr->op==TK_AND ){
testcase( jumpIfNull==0 );
sqlite3ExprIfFalse(pParse, pExpr->pLeft, dest, jumpIfNull);
sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
}else{
int d2 = sqlite3VdbeMakeLabel(pParse);
testcase( jumpIfNull==0 );
sqlite3ExprIfTrue(pParse, pExpr->pLeft, d2,
jumpIfNull^SQLITE_JUMPIFNULL);
sqlite3ExprIfFalse(pParse, pExpr->pRight, dest, jumpIfNull);
sqlite3VdbeResolveLabel(v, d2);
}
break;
}
case TK_NOT: {