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Enhance the code generator for INSERT INTO ... SELECT so that the SELECT

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generates output directly in the registers that INSERT INTO will be using,
in many cases, and OP_SCopy operations can thus be avoided.

FossilOrigin-Name: aa2d8b0e8154dd2f5e2c837dc11ab362b083495b
This commit is contained in:
drh
2014-02-16 01:55:49 +00:00
parent cfc6ca4179
commit 05a86c5c0f
9 changed files with 165 additions and 199 deletions
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42
src/expr.c
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@@ -3112,7 +3112,7 @@ int sqlite3ExprCodeTemp(Parse *pParse, Expr *pExpr, int *pReg){
** results in register target. The results are guaranteed to appear
** in register target.
*/
int sqlite3ExprCode(Parse *pParse, Expr *pExpr, int target){
void sqlite3ExprCode(Parse *pParse, Expr *pExpr, int target){
int inReg;
assert( target>0 && target<=pParse->nMem );
@@ -3125,7 +3125,20 @@ int sqlite3ExprCode(Parse *pParse, Expr *pExpr, int target){
sqlite3VdbeAddOp2(pParse->pVdbe, OP_SCopy, inReg, target);
}
}
return target;
}
/*
** Generate code that will evaluate expression pExpr and store the
** results in register target. The results are guaranteed to appear
** in register target. If the expression is constant, then this routine
** might choose to code the expression at initialization time.
*/
void sqlite3ExprCodeFactorable(Parse *pParse, Expr *pExpr, int target){
if( pParse->okConstFactor && sqlite3ExprIsConstant(pExpr) ){
sqlite3ExprCodeAtInit(pParse, pExpr, target, 0);
}else{
sqlite3ExprCode(pParse, pExpr, target);
}
}
/*
@@ -3140,25 +3153,16 @@ int sqlite3ExprCode(Parse *pParse, Expr *pExpr, int target){
** times. They are evaluated once and the results of the expression
** are reused.
*/
int sqlite3ExprCodeAndCache(Parse *pParse, Expr *pExpr, int target){
void sqlite3ExprCodeAndCache(Parse *pParse, Expr *pExpr, int target){
Vdbe *v = pParse->pVdbe;
int inReg;
inReg = sqlite3ExprCode(pParse, pExpr, target);
int iMem;
assert( target>0 );
/* The only place, other than this routine, where expressions can be
** converted to TK_REGISTER is internal subexpressions in BETWEEN and
** CASE operators. Neither ever calls this routine. And this routine
** is never called twice on the same expression. Hence it is impossible
** for the input to this routine to already be a register. Nevertheless,
** it seems prudent to keep the ALWAYS() in case the conditions above
** change with future modifications or enhancements. */
if( ALWAYS(pExpr->op!=TK_REGISTER) ){
int iMem;
iMem = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Copy, inReg, iMem);
exprToRegister(pExpr, iMem);
}
return inReg;
assert( pExpr->op!=TK_REGISTER );
sqlite3ExprCode(pParse, pExpr, target);
iMem = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Copy, target, iMem);
exprToRegister(pExpr, iMem);
}
#if defined(SQLITE_ENABLE_TREE_EXPLAIN)