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Refactor the sqlite3ExprCodeIN() routine for improved maintainability.

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FossilOrigin-Name: b56705ae6374db9db82613ef89faa1a1e6b00a18
This commit is contained in:
drh
2016-08-25 21:14:34 +00:00
parent 0a1082aec2
commit e347d3e813
4 changed files with 161 additions and 147 deletions
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271
src/expr.c
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@@ -2638,10 +2638,15 @@ int sqlite3ExprCheckIN(Parse *pParse, Expr *pIn){
** x IN (value, value, ...)
**
** The left-hand side (LHS) is a scalar or vector expression. The
** right-hand side (RHS) is an array of zero or more values. The IN operator
** is true if the LHS is contained within the RHS. The result is false
** if the LHS is definitely not in the RHS. The result is NULL if the presence
** of the LHS in the RHS cannot be determined due to NULLs.
** right-hand side (RHS) is an array of zero or more scalar values, or a
** subquery. If the RHS is a subquery, the number of result columns must
** match the number of columns in the vector on the LHS. If the RHS is
** a list of values, the LHS must be a scalar.
**
** The IN operator is true if the LHS value is contained within the RHS.
** The result is false if the LHS is definitely not in the RHS. The
** result is NULL if the presence of the LHS in the RHS cannot be
** determined due to NULLs.
**
** This routine generates code that jumps to destIfFalse if the LHS is not
** contained within the RHS. If due to NULLs we cannot determine if the LHS
@@ -2659,22 +2664,29 @@ static void sqlite3ExprCodeIN(
){
int rRhsHasNull = 0; /* Register that is true if RHS contains NULL values */
int eType; /* Type of the RHS */
int r1, r2; /* Temporary use registers */
int rLhs; /* Register(s) holding the LHS values */
int rLhsOrig; /* LHS values prior to reordering by aiMap[] */
Vdbe *v; /* Statement under construction */
int *aiMap = 0; /* Map from vector field to index column */
char *zAff = 0; /* Affinity string for comparisons */
int nVector; /* Size of vectors for this IN operator */
int iDummy; /* Dummy parameter to exprCodeVector() */
Expr *pLeft = pExpr->pLeft; /* The LHS of the IN operator */
int i; /* loop counter */
int nVector; /* Size of vectors for this IN operator */
int iDummy; /* Dummy parameter to exprCodeVector() */
Expr *pLeft; /* The LHS of the IN operator */
int i; /* loop counter */
int destStep2; /* Where to jump when NULLs seen in step 2 */
int destStep6 = 0; /* Start of code for Step 6 */
int addrTruthOp; /* Address of opcode that determines the IN is true */
int destNotNull; /* Jump here if a comparison is not true in step 6 */
int addrTop; /* Top of the step-6 loop */
pLeft = pExpr->pLeft;
if( sqlite3ExprCheckIN(pParse, pExpr) ) return;
zAff = exprINAffinity(pParse, pExpr);
nVector = sqlite3ExprVectorSize(pExpr->pLeft);
aiMap = (int*)sqlite3DbMallocZero(
pParse->db, nVector*(sizeof(int) + sizeof(char)) + 1
);
if( pParse->db->mallocFailed ) goto end_code_IN_op;
if( pParse->db->mallocFailed ) goto sqlite3ExprCodeIN_oom_error;
/* Attempt to compute the RHS. After this step, if anything other than
** IN_INDEX_NOOP is returned, the table opened ith cursor pExpr->iTable
@@ -2703,24 +2715,31 @@ static void sqlite3ExprCodeIN(
/* Code the LHS, the <expr> from "<expr> IN (...)". If the LHS is a
** vector, then it is stored in an array of nVector registers starting
** at r1.
**
** sqlite3FindInIndex() might have reordered the fields of the LHS vector
** so that the fields are in the same order as an existing index. The
** aiMap[] array contains a mapping from the original LHS field order to
** the field order that matches the RHS index.
*/
sqlite3ExprCachePush(pParse);
r2 = exprCodeVector(pParse, pLeft, &iDummy);
for(i=0; i<nVector && aiMap[i]==i; i++){}
rLhsOrig = exprCodeVector(pParse, pLeft, &iDummy);
for(i=0; i<nVector && aiMap[i]==i; i++){} /* Are LHS fields reordered? */
if( i==nVector ){
/* LHS fields are already in the correct order */
r1 = r2;
/* LHS fields are not reordered */
rLhs = rLhsOrig;
}else{
/* Need to reorder the LHS fields according to aiMap */
r1 = sqlite3GetTempRange(pParse, nVector);
rLhs = sqlite3GetTempRange(pParse, nVector);
for(i=0; i<nVector; i++){
sqlite3VdbeAddOp3(v, OP_Copy, r2+i, r1+aiMap[i], 0);
sqlite3VdbeAddOp3(v, OP_Copy, rLhsOrig+i, rLhs+aiMap[i], 0);
}
}
/* If sqlite3FindInIndex() did not find or create an index that is
** suitable for evaluating the IN operator, then evaluate using a
** sequence of comparisons.
**
** This is step (1) in the in-operator.md optimized algorithm.
*/
if( eType==IN_INDEX_NOOP ){
ExprList *pList = pExpr->x.pList;
@@ -2732,7 +2751,7 @@ static void sqlite3ExprCodeIN(
assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
if( destIfNull!=destIfFalse ){
regCkNull = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_BitAnd, r1, r1, regCkNull);
sqlite3VdbeAddOp3(v, OP_BitAnd, rLhs, rLhs, regCkNull);
}
for(ii=0; ii<pList->nExpr; ii++){
r2 = sqlite3ExprCodeTemp(pParse, pList->a[ii].pExpr, &regToFree);
@@ -2740,14 +2759,14 @@ static void sqlite3ExprCodeIN(
sqlite3VdbeAddOp3(v, OP_BitAnd, regCkNull, r2, regCkNull);
}
if( ii<pList->nExpr-1 || destIfNull!=destIfFalse ){
sqlite3VdbeAddOp4(v, OP_Eq, r1, labelOk, r2,
sqlite3VdbeAddOp4(v, OP_Eq, rLhs, labelOk, r2,
(void*)pColl, P4_COLLSEQ);
VdbeCoverageIf(v, ii<pList->nExpr-1);
VdbeCoverageIf(v, ii==pList->nExpr-1);
sqlite3VdbeChangeP5(v, zAff[0]);
}else{
assert( destIfNull==destIfFalse );
sqlite3VdbeAddOp4(v, OP_Ne, r1, destIfFalse, r2,
sqlite3VdbeAddOp4(v, OP_Ne, rLhs, destIfFalse, r2,
(void*)pColl, P4_COLLSEQ); VdbeCoverage(v);
sqlite3VdbeChangeP5(v, zAff[0] | SQLITE_JUMPIFNULL);
}
@@ -2759,127 +2778,111 @@ static void sqlite3ExprCodeIN(
}
sqlite3VdbeResolveLabel(v, labelOk);
sqlite3ReleaseTempReg(pParse, regCkNull);
goto sqlite3ExprCodeIN_finished;
}
/* Step 2: Check to see if the LHS contains any NULL columns. If the
** LHS does contain NULLs then the result must be either FALSE or NULL.
** We will then skip the binary search of the RHS.
*/
if( destIfNull==destIfFalse ){
destStep2 = destIfFalse;
}else{
/* If any value on the LHS is NULL, the result of the IN(...) operator
** must be either false or NULL. If these two are handled identically,
** test the LHS for NULLs and jump directly to destIfNull if any are
** found.
**
** Otherwise, if NULL and false are handled differently, and the
** IN(...) operation is not a vector operation, and the LHS of the
** operator is NULL, then the result is false if the index is
** completely empty, or NULL otherwise. */
if( destIfNull==destIfFalse ){
for(i=0; i<nVector; i++){
Expr *p = sqlite3VectorFieldSubexpr(pExpr->pLeft, i);
if( sqlite3ExprCanBeNull(p) ){
sqlite3VdbeAddOp2(v, OP_IsNull, r1+aiMap[i], destIfNull);
VdbeCoverage(v);
}
}
}else if( nVector==1 && sqlite3ExprCanBeNull(pExpr->pLeft) ){
int addr1 = sqlite3VdbeAddOp1(v, OP_NotNull, r1); VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_Rewind, pExpr->iTable, destIfFalse);
destStep2 = destStep6 = sqlite3VdbeMakeLabel(v);
}
for(i=0; i<nVector; i++){
Expr *p = sqlite3VectorFieldSubexpr(pExpr->pLeft, i);
if( sqlite3ExprCanBeNull(p) ){
sqlite3VdbeAddOp2(v, OP_IsNull, rLhs+i, destStep2);
VdbeCoverage(v);
sqlite3VdbeGoto(v, destIfNull);
sqlite3VdbeJumpHere(v, addr1);
}
if( eType==IN_INDEX_ROWID ){
/* In this case, the RHS is the ROWID of table b-tree */
sqlite3VdbeAddOp3(v, OP_SeekRowid, pExpr->iTable, destIfFalse, r1);
VdbeCoverage(v);
}else{
/* In this case, the RHS is an index b-tree. Apply the comparison
** affinities to each value on the LHS of the operator. */
sqlite3VdbeAddOp4(v, OP_Affinity, r1, nVector, 0, zAff, nVector);
if( nVector>1 && destIfNull!=destIfFalse ){
int iIdx = pExpr->iTable;
int addrTop;
int addrNext;
int addrFound;
/* Search the index for the key. */
addrFound = sqlite3VdbeAddOp4Int(v, OP_Found, iIdx, 0, r1, nVector);
VdbeCoverage(v);
/* At this point the specified key is not present in the index,
** so the result of the IN(..) operator must be either NULL or
** 0. The vdbe code generated below figures out which. */
addrTop = 1+sqlite3VdbeAddOp2(v, OP_Rewind, iIdx, destIfFalse);
VdbeCoverage(v);
addrNext = sqlite3VdbeMakeLabel(v);
for(i=0; i<nVector; i++){
Expr *p;
CollSeq *pColl;
int r2 = sqlite3GetTempReg(pParse);
p = sqlite3VectorFieldSubexpr(pLeft, i);
pColl = sqlite3ExprCollSeq(pParse, p);
sqlite3VdbeAddOp3(v, OP_Column, iIdx, i, r2);
sqlite3VdbeAddOp4(v, OP_Ne, r1+i, addrNext, r2,
(void*)pColl, P4_COLLSEQ);
VdbeCoverage(v);
sqlite3ReleaseTempReg(pParse, r2);
}
sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfNull);
sqlite3VdbeResolveLabel(v, addrNext);
sqlite3VdbeAddOp2(v, OP_Next, iIdx, addrTop);
VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfFalse);
/* The key was found in the index. If it contains any NULL values,
** then the result of the IN(...) operator is NULL. Otherwise, the
** result is 1. */
sqlite3VdbeJumpHere(v, addrFound);
for(i=0; i<nVector; i++){
Expr *p = sqlite3VectorFieldSubexpr(pExpr->pLeft, i);
if( sqlite3ExprCanBeNull(p) ){
sqlite3VdbeAddOp2(v, OP_IsNull, r1+aiMap[i], destIfNull);
VdbeCoverage(v);
}
}
}else if( rRhsHasNull==0 ){
/* This branch runs if it is known at compile time that the RHS
** cannot contain NULL values. This happens as a result
** of "NOT NULL" constraints in the database schema.
**
** Also run this branch if NULL is equivalent to FALSE
** for this particular IN operator. */
sqlite3VdbeAddOp4Int(
v, OP_NotFound, pExpr->iTable, destIfFalse, r1, nVector
);
VdbeCoverage(v);
}else{
/* In this branch, the RHS of the IN might contain a NULL and
** the presence of a NULL on the RHS makes a difference in the
** outcome.
*/
int addr1;
/* First check to see if the LHS is contained in the RHS. If so,
** then the answer is TRUE the presence of NULLs in the RHS does
** not matter. If the LHS is not contained in the RHS, then the
** answer is NULL if the RHS contains NULLs and the answer is
** FALSE if the RHS is NULL-free.
*/
addr1 = sqlite3VdbeAddOp4Int(v, OP_Found, pExpr->iTable, 0, r1, 1);
VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_IsNull, rRhsHasNull, destIfNull);
VdbeCoverage(v);
sqlite3VdbeGoto(v, destIfFalse);
sqlite3VdbeJumpHere(v, addr1);
}
}
}
if( r2!=r1 ) sqlite3ReleaseTempReg(pParse, r1);
/* Step 3. The LHS is now known to be non-NULL. Do the binary search
** of the RHS using the LHS as a probe. If found, the result is
** true.
*/
if( eType==IN_INDEX_ROWID ){
/* In this case, the RHS is the ROWID of table b-tree and so we also
** know that the RHS is non-NULL. Hence, we combine steps 3 and 4
** into a single opcode. */
sqlite3VdbeAddOp3(v, OP_SeekRowid, pExpr->iTable, destIfFalse, rLhs);
VdbeCoverage(v);
addrTruthOp = sqlite3VdbeAddOp0(v, OP_Goto); /* Return True */
}else{
sqlite3VdbeAddOp4(v, OP_Affinity, rLhs, nVector, 0, zAff, nVector);
if( destIfFalse==destIfNull ){
/* Combine Step 3 and Step 5 into a single opcode */
sqlite3VdbeAddOp4Int(v, OP_NotFound, pExpr->iTable, destIfFalse,
rLhs, nVector); VdbeCoverage(v);
goto sqlite3ExprCodeIN_finished;
}
/* Ordinary Step 3, for the case where FALSE and NULL are distinct */
addrTruthOp = sqlite3VdbeAddOp4Int(v, OP_Found, pExpr->iTable, 0,
rLhs, nVector); VdbeCoverage(v);
}
/* Step 4. If the RHS is known to be non-NULL and we did not find
** an match on the search above, then the result must be FALSE.
*/
if( rRhsHasNull && nVector==1 ){
sqlite3VdbeAddOp2(v, OP_NotNull, rRhsHasNull, destIfFalse);
VdbeCoverage(v);
}
/* Step 5. If we do not care about the difference between NULL and
** FALSE, then just return false.
*/
if( destIfFalse==destIfNull ) sqlite3VdbeGoto(v, destIfFalse);
/* Step 6: Loop through rows of the RHS. Compare each row to the LHS.
** If any comparison is NULL, then the result is NULL. If all
** comparisons are FALSE then the final result is FALSE.
**
** For a scalar LHS, it is sufficient to check just the first row
** of the RHS.
*/
if( destStep6 ) sqlite3VdbeResolveLabel(v, destStep6);
addrTop = sqlite3VdbeAddOp2(v, OP_Rewind, pExpr->iTable, destIfFalse);
VdbeCoverage(v);
if( nVector>1 ){
destNotNull = sqlite3VdbeMakeLabel(v);
}else{
/* For nVector==1, combine steps 6 and 7 by immediately returning
** FALSE if the first comparison is not NULL */
destNotNull = destIfFalse;
}
for(i=0; i<nVector; i++){
Expr *p;
CollSeq *pColl;
int r3 = sqlite3GetTempReg(pParse);
p = sqlite3VectorFieldSubexpr(pLeft, i);
pColl = sqlite3ExprCollSeq(pParse, p);
sqlite3VdbeAddOp3(v, OP_Column, pExpr->iTable, i, r3);
sqlite3VdbeAddOp4(v, OP_Ne, rLhs+i, destNotNull, r3,
(void*)pColl, P4_COLLSEQ);
VdbeCoverage(v);
sqlite3ReleaseTempReg(pParse, r3);
}
sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfNull);
if( nVector>1 ){
sqlite3VdbeResolveLabel(v, destNotNull);
sqlite3VdbeAddOp2(v, OP_Next, pExpr->iTable, addrTop+1);
VdbeCoverage(v);
/* Step 7: If we reach this point, we know that the result must
** be false. */
sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfFalse);
}
/* Jumps here in order to return true. */
sqlite3VdbeJumpHere(v, addrTruthOp);
sqlite3ExprCodeIN_finished:
if( rLhs!=rLhsOrig ) sqlite3ReleaseTempReg(pParse, rLhs);
sqlite3ExprCachePop(pParse);
VdbeComment((v, "end IN expr"));
end_code_IN_op:
sqlite3ExprCodeIN_oom_error:
sqlite3DbFree(pParse->db, aiMap);
sqlite3DbFree(pParse->db, zAff);
}