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Overview
Comment:Suppress more instances of unnecessary OP_IsNull and OP_Affinity opcodes.
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SHA1: bf6c0bd1c5568c6292ea0a64c8a5071e1bd3079a
User & Date: drh 2009-11-18 01:25:27
Context
2009-11-18
23:01
Performance improvement by avoiding unnecessary calls to memset(). check-in: 85940468 user: drh tags: trunk
01:25
Suppress more instances of unnecessary OP_IsNull and OP_Affinity opcodes. check-in: bf6c0bd1 user: drh tags: trunk
2009-11-17
23:59
Enhancements to the VDBE opcode loop to reduce the number of machine-code instructions evaluated by about 10%. check-in: 9744ffb3 user: drh tags: trunk
Changes
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Changes to src/expr.c.

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    case TK_FLOAT:
    case TK_BLOB:
      return 0;
    default:
      return 1;
  }
}



















/*
** Return TRUE if the given expression is a constant which would be
** unchanged by OP_Affinity with the affinity given in the second
** argument.
**
** This routine is used to determine if the OP_Affinity operation
................................................................................
    }
    case TK_STRING: {
      return aff==SQLITE_AFF_TEXT;
    }
    case TK_BLOB: {
      return 1;
    }




    default: {
      return 0;
    }
  }
}

/*







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    case TK_FLOAT:
    case TK_BLOB:
      return 0;
    default:
      return 1;
  }
}

/*
** Generate an OP_IsNull instruction that tests register iReg and jumps
** to location iDest if the value in iReg is NULL.  The value in iReg 
** was computed by pExpr.  If we can look at pExpr at compile-time and
** determine that it can never generate a NULL, then the OP_IsNull operation
** can be omitted.
*/
void sqlite3ExprCodeIsNullJump(
  Vdbe *v,            /* The VDBE under construction */
  const Expr *pExpr,  /* Only generate OP_IsNull if this expr can be NULL */
  int iReg,           /* Test the value in this register for NULL */
  int iDest           /* Jump here if the value is null */
){
  if( sqlite3ExprCanBeNull(pExpr) ){
    sqlite3VdbeAddOp2(v, OP_IsNull, iReg, iDest);
  }
}

/*
** Return TRUE if the given expression is a constant which would be
** unchanged by OP_Affinity with the affinity given in the second
** argument.
**
** This routine is used to determine if the OP_Affinity operation
................................................................................
    }
    case TK_STRING: {
      return aff==SQLITE_AFF_TEXT;
    }
    case TK_BLOB: {
      return 1;
    }
    case TK_COLUMN: {
      return p->iTable>=0 && p->iColumn<0
               && (aff==SQLITE_AFF_INTEGER || aff==SQLITE_AFF_NUMERIC);
    }
    default: {
      return 0;
    }
  }
}

/*

Changes to src/sqliteInt.h.

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void sqlite3Savepoint(Parse*, int, Token*);
void sqlite3CloseSavepoints(sqlite3 *);
int sqlite3ExprIsConstant(Expr*);
int sqlite3ExprIsConstantNotJoin(Expr*);
int sqlite3ExprIsConstantOrFunction(Expr*);
int sqlite3ExprIsInteger(Expr*, int*);
int sqlite3ExprCanBeNull(const Expr*);

int sqlite3ExprNeedsNoAffinityChange(const Expr*, char);
int sqlite3IsRowid(const char*);
void sqlite3GenerateRowDelete(Parse*, Table*, int, int, int, Trigger *, int);
void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int*);
int sqlite3GenerateIndexKey(Parse*, Index*, int, int, int);
void sqlite3GenerateConstraintChecks(Parse*,Table*,int,int,
                                     int*,int,int,int,int,int*);







>







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void sqlite3Savepoint(Parse*, int, Token*);
void sqlite3CloseSavepoints(sqlite3 *);
int sqlite3ExprIsConstant(Expr*);
int sqlite3ExprIsConstantNotJoin(Expr*);
int sqlite3ExprIsConstantOrFunction(Expr*);
int sqlite3ExprIsInteger(Expr*, int*);
int sqlite3ExprCanBeNull(const Expr*);
void sqlite3ExprCodeIsNullJump(Vdbe*, const Expr*, int, int);
int sqlite3ExprNeedsNoAffinityChange(const Expr*, char);
int sqlite3IsRowid(const char*);
void sqlite3GenerateRowDelete(Parse*, Table*, int, int, int, Trigger *, int);
void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int*);
int sqlite3GenerateIndexKey(Parse*, Index*, int, int, int);
void sqlite3GenerateConstraintChecks(Parse*,Table*,int,int,
                                     int*,int,int,int,int,int*);

Changes to src/where.c.

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        sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j);
      }
    }
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_IN );
    if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){
      Expr *pRight = pTerm->pExpr->pRight;
      if( sqlite3ExprCanBeNull(pRight) ){
        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->addrBrk);
      }
      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_NONE ){
          zAff[j] = SQLITE_AFF_NONE;
        }
        if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[j]) ){
          zAff[j] = SQLITE_AFF_NONE;
        }
................................................................................
    start_constraints = pRangeStart || nEq>0;

    /* Seek the index cursor to the start of the range. */
    nConstraint = nEq;
    if( pRangeStart ){
      Expr *pRight = pRangeStart->pExpr->pRight;
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[nConstraint])==SQLITE_AFF_NONE){
          /* Since the comparison is to be performed with no conversions
          ** applied to the operands, set the affinity to apply to pRight to 
          ** SQLITE_AFF_NONE.  */
          zAff[nConstraint] = SQLITE_AFF_NONE;
        }
................................................................................
    ** range (if any).
    */
    nConstraint = nEq;
    if( pRangeEnd ){
      Expr *pRight = pRangeEnd->pExpr->pRight;
      sqlite3ExprCacheRemove(pParse, regBase+nEq);
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[nConstraint])==SQLITE_AFF_NONE){
          /* Since the comparison is to be performed with no conversions
          ** applied to the operands, set the affinity to apply to pRight to 
          ** SQLITE_AFF_NONE.  */
          zAff[nConstraint] = SQLITE_AFF_NONE;
        }







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        sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j);
      }
    }
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_IN );
    if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){
      Expr *pRight = pTerm->pExpr->pRight;

      sqlite3ExprCodeIsNullJump(v, pRight, regBase+j, pLevel->addrBrk);

      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_NONE ){
          zAff[j] = SQLITE_AFF_NONE;
        }
        if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[j]) ){
          zAff[j] = SQLITE_AFF_NONE;
        }
................................................................................
    start_constraints = pRangeStart || nEq>0;

    /* Seek the index cursor to the start of the range. */
    nConstraint = nEq;
    if( pRangeStart ){
      Expr *pRight = pRangeStart->pExpr->pRight;
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      sqlite3ExprCodeIsNullJump(v, pRight, regBase+nEq, addrNxt);
      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[nConstraint])==SQLITE_AFF_NONE){
          /* Since the comparison is to be performed with no conversions
          ** applied to the operands, set the affinity to apply to pRight to 
          ** SQLITE_AFF_NONE.  */
          zAff[nConstraint] = SQLITE_AFF_NONE;
        }
................................................................................
    ** range (if any).
    */
    nConstraint = nEq;
    if( pRangeEnd ){
      Expr *pRight = pRangeEnd->pExpr->pRight;
      sqlite3ExprCacheRemove(pParse, regBase+nEq);
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      sqlite3ExprCodeIsNullJump(v, pRight, regBase+nEq, addrNxt);
      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[nConstraint])==SQLITE_AFF_NONE){
          /* Since the comparison is to be performed with no conversions
          ** applied to the operands, set the affinity to apply to pRight to 
          ** SQLITE_AFF_NONE.  */
          zAff[nConstraint] = SQLITE_AFF_NONE;
        }