Enhance the code generator for INSERT INTO ... SELECT so that the SELECT
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
diff --git a/src/expr.c b/src/expr.c
index 0f07181..79b50fb 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -3112,7 +3112,7 @@
** 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 @@
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 @@
** 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)