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Clean up the implementation of constant function factorization.

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FossilOrigin-Name: 2ab997e47998d261bd6190bbce5c09f3fbd4cfd3
This commit is contained in:
drh
2017-01-04 04:10:02 +00:00
parent 1e9b53f9bc
commit ad879ffdb5
4 changed files with 29 additions and 35 deletions
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43
src/expr.c
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@@ -3613,7 +3613,9 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
CollSeq *pColl = 0; /* A collating sequence */
if( ConstFactorOk(pParse) && sqlite3ExprIsConstantNotJoin(pExpr) ){
return sqlite3ExprCodeAtInit(pParse, pExpr, -1, 1);
/* SQL function can be expensive. So try to move constant functions
** out of the inner loop, even if that means an extra OP_Copy. */
return sqlite3ExprCodeAtInit(pParse, pExpr, -1);
}
assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
if( ExprHasProperty(pExpr, EP_TokenOnly) ){
@@ -3996,41 +3998,36 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
/*
** Factor out the code of the given expression to initialization time.
**
** If regDest>=0 then the result is always stored in that register.
** If regDest<0 then this routine is free to store the value whereever
** it wants. The register where the expression is stored is returned.
**
** If regDest<0 and an equivalent expression already exists elsewhere
** in the initialization expressions, then routine just returns the
** register of the prior occurrance.
** If regDest>=0 then the result is always stored in that register and the
** result is not reusable. If regDest<0 then this routine is free to
** store the value whereever it wants. The register where the expression
** is stored is returned. When regDest<0, two identical expressions will
** code to the same register.
*/
int sqlite3ExprCodeAtInit(
Parse *pParse, /* Parsing context */
Expr *pExpr, /* The expression to code when the VDBE initializes */
int regDest, /* Store the value in this register */
u8 reusable /* True if this expression is reusable */
int regDest /* Store the value in this register */
){
ExprList *p;
assert( ConstFactorOk(pParse) );
p = pParse->pConstExpr;
if( regDest<0 ){
if( p && reusable ){
struct ExprList_item *pItem;
int i;
for(pItem=p->a, i=p->nExpr; i>0; pItem++, i--){
if( pItem->reusable && sqlite3ExprCompare(pItem->pExpr,pExpr,-1)==0 ){
return pItem->u.iConstExprReg;
}
if( regDest<0 && p ){
struct ExprList_item *pItem;
int i;
for(pItem=p->a, i=p->nExpr; i>0; pItem++, i--){
if( pItem->reusable && sqlite3ExprCompare(pItem->pExpr,pExpr,-1)==0 ){
return pItem->u.iConstExprReg;
}
}
regDest = ++pParse->nMem;
}
pExpr = sqlite3ExprDup(pParse->db, pExpr, 0);
p = sqlite3ExprListAppend(pParse, p, pExpr);
if( p ){
struct ExprList_item *pItem = &p->a[p->nExpr-1];
pItem->reusable = regDest<0;
if( regDest<0 ) regDest = ++pParse->nMem;
pItem->u.iConstExprReg = regDest;
pItem->reusable = reusable;
}
pParse->pConstExpr = p;
return regDest;
@@ -4057,7 +4054,7 @@ int sqlite3ExprCodeTemp(Parse *pParse, Expr *pExpr, int *pReg){
&& sqlite3ExprIsConstantNotJoin(pExpr)
){
*pReg = 0;
r2 = sqlite3ExprCodeAtInit(pParse, pExpr, -1, 1);
r2 = sqlite3ExprCodeAtInit(pParse, pExpr, -1);
}else{
int r1 = sqlite3GetTempReg(pParse);
r2 = sqlite3ExprCodeTarget(pParse, pExpr, r1);
@@ -4111,7 +4108,7 @@ void sqlite3ExprCodeCopy(Parse *pParse, Expr *pExpr, int target){
*/
void sqlite3ExprCodeFactorable(Parse *pParse, Expr *pExpr, int target){
if( pParse->okConstFactor && sqlite3ExprIsConstant(pExpr) ){
sqlite3ExprCodeAtInit(pParse, pExpr, target, 0);
sqlite3ExprCodeAtInit(pParse, pExpr, target);
}else{
sqlite3ExprCode(pParse, pExpr, target);
}
@@ -4183,7 +4180,7 @@ int sqlite3ExprCodeExprList(
sqlite3VdbeAddOp2(v, copyOp, j+srcReg-1, target+i);
}
}else if( (flags & SQLITE_ECEL_FACTOR)!=0 && sqlite3ExprIsConstant(pExpr) ){
sqlite3ExprCodeAtInit(pParse, pExpr, target+i, 0);
sqlite3ExprCodeAtInit(pParse, pExpr, target+i);
}else{
int inReg = sqlite3ExprCodeTarget(pParse, pExpr, target+i);
if( inReg!=target+i ){