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Evaluate expressions only once when the same expression is used in both the

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result set and in the ORDER BY clause.

FossilOrigin-Name: c2f3bbad778504681b39ab9399a1eb3c1a35ab3f
This commit is contained in:
drh
2015-08-26 14:01:41 +00:00
parent 0576bc59a7
commit 5579d59fb3
8 changed files with 93 additions and 26 deletions
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11
src/expr.c
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@@ -2912,7 +2912,7 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
}
sqlite3ExprCachePush(pParse); /* Ticket 2ea2425d34be */
sqlite3ExprCodeExprList(pParse, pFarg, r1,
sqlite3ExprCodeExprList(pParse, pFarg, r1, 0,
SQLITE_ECEL_DUP|SQLITE_ECEL_FACTOR);
sqlite3ExprCachePop(pParse); /* Ticket 2ea2425d34be */
}else{
@@ -3328,11 +3328,13 @@ int sqlite3ExprCodeExprList(
Parse *pParse, /* Parsing context */
ExprList *pList, /* The expression list to be coded */
int target, /* Where to write results */
int srcReg, /* Source registers if SQLITE_ECEL_REF */
u8 flags /* SQLITE_ECEL_* flags */
){
struct ExprList_item *pItem;
int i, n;
int i, j, n;
u8 copyOp = (flags & SQLITE_ECEL_DUP) ? OP_Copy : OP_SCopy;
Vdbe *v = pParse->pVdbe;
assert( pList!=0 );
assert( target>0 );
assert( pParse->pVdbe!=0 ); /* Never gets this far otherwise */
@@ -3340,13 +3342,14 @@ int sqlite3ExprCodeExprList(
if( !ConstFactorOk(pParse) ) flags &= ~SQLITE_ECEL_FACTOR;
for(pItem=pList->a, i=0; i<n; i++, pItem++){
Expr *pExpr = pItem->pExpr;
if( (flags & SQLITE_ECEL_FACTOR)!=0 && sqlite3ExprIsConstant(pExpr) ){
if( (flags & SQLITE_ECEL_REF)!=0 && (j = pList->a[i].u.x.iOrderByCol)>0 ){
sqlite3VdbeAddOp2(v, copyOp, j+srcReg-1, target+i);
}else if( (flags & SQLITE_ECEL_FACTOR)!=0 && sqlite3ExprIsConstant(pExpr) ){
sqlite3ExprCodeAtInit(pParse, pExpr, target+i, 0);
}else{
int inReg = sqlite3ExprCodeTarget(pParse, pExpr, target+i);
if( inReg!=target+i ){
VdbeOp *pOp;
Vdbe *v = pParse->pVdbe;
if( copyOp==OP_Copy
&& (pOp=sqlite3VdbeGetOp(v, -1))->opcode==OP_Copy
&& pOp->p1+pOp->p3+1==inReg