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Overview
Comment:Remove an unnecessary parameter from selectInnerLoop().
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SHA3-256: dd95887f82739d05585edfb70913fdaaab154de46c4d3113dd32d283767fb6fc
User & Date: drh 2017-09-15 17:40:34
Context
2017-09-16
20:58
Simplify the sqlite3VdbeGet() routine. Smaller, faster, and easier to maintain. check-in: 5dbb255a user: drh tags: trunk
2017-09-15
17:40
Remove an unnecessary parameter from selectInnerLoop(). check-in: dd95887f user: drh tags: trunk
15:38
Improved the header-comment documentation on sqlite3ExprCodeExprList(). No changes to code. check-in: 5dc3ecb5 user: drh tags: trunk
Changes
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Changes to src/select.c.

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  sqlite3ReleaseTempReg(pParse, r1);
}

/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**
** If srcTab is negative, then the pEList expressions
** are evaluated in order to get the data for this row.  If srcTab is
** zero or more, then data is pulled from srcTab and pEList is used only 
** to get the number of columns and the collation sequence for each column.
*/
static void selectInnerLoop(
  Parse *pParse,          /* The parser context */
  Select *p,              /* The complete select statement being coded */
  ExprList *pEList,       /* List of values being extracted */
  int srcTab,             /* Pull data from this table */
  SortCtx *pSort,         /* If not NULL, info on how to process ORDER BY */
  DistinctCtx *pDistinct, /* If not NULL, info on how to process DISTINCT */
  SelectDest *pDest,      /* How to dispose of the results */
  int iContinue,          /* Jump here to continue with next row */
  int iBreak              /* Jump here to break out of the inner loop */
){
  Vdbe *v = pParse->pVdbe;
................................................................................
  ** same value. However, if the results are being sent to the sorter, the
  ** values for any expressions that are also part of the sort-key are omitted
  ** from this array. In this case regOrig is set to zero.  */
  int regResult;              /* Start of memory holding current results */
  int regOrig;                /* Start of memory holding full result (or 0) */

  assert( v );
  assert( pEList!=0 );
  hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP;
  if( pSort && pSort->pOrderBy==0 ) pSort = 0;
  if( pSort==0 && !hasDistinct ){
    assert( iContinue!=0 );
    codeOffset(v, p->iOffset, iContinue);
  }

  /* Pull the requested columns.
  */
  nResultCol = pEList->nExpr;

  if( pDest->iSdst==0 ){
    if( pSort ){
      nPrefixReg = pSort->pOrderBy->nExpr;
      if( !(pSort->sortFlags & SORTFLAG_UseSorter) ) nPrefixReg++;
      pParse->nMem += nPrefixReg;
    }
................................................................................
    pParse->nMem += nResultCol;
  }
  pDest->nSdst = nResultCol;
  regOrig = regResult = pDest->iSdst;
  if( srcTab>=0 ){
    for(i=0; i<nResultCol; i++){
      sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
      VdbeComment((v, "%s", pEList->a[i].zName));
    }
  }else if( eDest!=SRT_Exists ){
    /* If the destination is an EXISTS(...) expression, the actual
    ** values returned by the SELECT are not required.
    */
    u8 ecelFlags;
    if( eDest==SRT_Mem || eDest==SRT_Output || eDest==SRT_Coroutine ){
      ecelFlags = SQLITE_ECEL_DUP;
    }else{
      ecelFlags = 0;
    }
    if( pSort && hasDistinct==0 && eDest!=SRT_EphemTab && eDest!=SRT_Table ){
      /* For each expression in pEList that is a copy of an expression in
      ** the ORDER BY clause (pSort->pOrderBy), set the associated 
      ** iOrderByCol value to one more than the index of the ORDER BY 
      ** expression within the sort-key that pushOntoSorter() will generate.
      ** This allows the pEList field to be omitted from the sorted record,
      ** saving space and CPU cycles.  */
      ecelFlags |= (SQLITE_ECEL_OMITREF|SQLITE_ECEL_REF);
      for(i=pSort->nOBSat; i<pSort->pOrderBy->nExpr; i++){
        int j;
        if( (j = pSort->pOrderBy->a[i].u.x.iOrderByCol)>0 ){
          pEList->a[j-1].u.x.iOrderByCol = i+1-pSort->nOBSat;
        }
      }
      regOrig = 0;
      assert( eDest==SRT_Set || eDest==SRT_Mem 
           || eDest==SRT_Coroutine || eDest==SRT_Output );
    }
    nResultCol = sqlite3ExprCodeExprList(pParse,pEList,regResult,0,ecelFlags);
  }

  /* If the DISTINCT keyword was present on the SELECT statement
  ** and this row has been seen before, then do not make this row
  ** part of the result.
  */
  if( hasDistinct ){
................................................................................
        pOp = sqlite3VdbeGetOp(v, pDistinct->addrTnct);
        pOp->opcode = OP_Null;
        pOp->p1 = 1;
        pOp->p2 = regPrev;

        iJump = sqlite3VdbeCurrentAddr(v) + nResultCol;
        for(i=0; i<nResultCol; i++){
          CollSeq *pColl = sqlite3ExprCollSeq(pParse, pEList->a[i].pExpr);
          if( i<nResultCol-1 ){
            sqlite3VdbeAddOp3(v, OP_Ne, regResult+i, iJump, regPrev+i);
            VdbeCoverage(v);
          }else{
            sqlite3VdbeAddOp3(v, OP_Eq, regResult+i, iContinue, regPrev+i);
            VdbeCoverage(v);
           }
................................................................................
    sqlite3VdbeAddOp2(v, OP_RowData, iQueue, regCurrent);
  }
  sqlite3VdbeAddOp1(v, OP_Delete, iQueue);

  /* Output the single row in Current */
  addrCont = sqlite3VdbeMakeLabel(v);
  codeOffset(v, regOffset, addrCont);
  selectInnerLoop(pParse, p, p->pEList, iCurrent,
      0, 0, pDest, addrCont, addrBreak);
  if( regLimit ){
    sqlite3VdbeAddOp2(v, OP_DecrJumpZero, regLimit, addrBreak);
    VdbeCoverage(v);
  }
  sqlite3VdbeResolveLabel(v, addrCont);

................................................................................
        int iCont, iBreak, iStart;
        assert( p->pEList );
        iBreak = sqlite3VdbeMakeLabel(v);
        iCont = sqlite3VdbeMakeLabel(v);
        computeLimitRegisters(pParse, p, iBreak);
        sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak); VdbeCoverage(v);
        iStart = sqlite3VdbeCurrentAddr(v);
        selectInnerLoop(pParse, p, p->pEList, unionTab,
                        0, 0, &dest, iCont, iBreak);
        sqlite3VdbeResolveLabel(v, iCont);
        sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart); VdbeCoverage(v);
        sqlite3VdbeResolveLabel(v, iBreak);
        sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0);
      }
      break;
................................................................................
      iCont = sqlite3VdbeMakeLabel(v);
      computeLimitRegisters(pParse, p, iBreak);
      sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak); VdbeCoverage(v);
      r1 = sqlite3GetTempReg(pParse);
      iStart = sqlite3VdbeAddOp2(v, OP_RowData, tab1, r1);
      sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0); VdbeCoverage(v);
      sqlite3ReleaseTempReg(pParse, r1);
      selectInnerLoop(pParse, p, p->pEList, tab1,
                      0, 0, &dest, iCont, iBreak);
      sqlite3VdbeResolveLabel(v, iCont);
      sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart); VdbeCoverage(v);
      sqlite3VdbeResolveLabel(v, iBreak);
      sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
      sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
      break;
................................................................................
    ** into an OP_Noop.
    */
    if( sSort.addrSortIndex>=0 && sSort.pOrderBy==0 ){
      sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex);
    }

    /* Use the standard inner loop. */

    selectInnerLoop(pParse, p, pEList, -1, &sSort, &sDistinct, pDest,
                    sqlite3WhereContinueLabel(pWInfo),
                    sqlite3WhereBreakLabel(pWInfo));

    /* End the database scan loop.
    */
    sqlite3WhereEnd(pWInfo);
  }else{
................................................................................
      addrOutputRow = sqlite3VdbeCurrentAddr(v);
      sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
      VdbeCoverage(v);
      VdbeComment((v, "Groupby result generator entry point"));
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      finalizeAggFunctions(pParse, &sAggInfo);
      sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
      selectInnerLoop(pParse, p, p->pEList, -1, &sSort,
                      &sDistinct, pDest,
                      addrOutputRow+1, addrSetAbort);
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      VdbeComment((v, "end groupby result generator"));

      /* Generate a subroutine that will reset the group-by accumulator
      */
................................................................................
        }
        sqlite3WhereEnd(pWInfo);
        finalizeAggFunctions(pParse, &sAggInfo);
      }

      sSort.pOrderBy = 0;
      sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
      selectInnerLoop(pParse, p, p->pEList, -1, 0, 0, 
                      pDest, addrEnd, addrEnd);
      sqlite3ExprListDelete(db, pDel);
    }
    sqlite3VdbeResolveLabel(v, addrEnd);
    
  } /* endif aggregate query */








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  sqlite3ReleaseTempReg(pParse, r1);
}

/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**
** If srcTab is negative, then the p->pEList expressions
** are evaluated in order to get the data for this row.  If srcTab is
** zero or more, then data is pulled from srcTab and p->pEList is used only 
** to get the number of columns and the collation sequence for each column.
*/
static void selectInnerLoop(
  Parse *pParse,          /* The parser context */
  Select *p,              /* The complete select statement being coded */

  int srcTab,             /* Pull data from this table if non-negative */
  SortCtx *pSort,         /* If not NULL, info on how to process ORDER BY */
  DistinctCtx *pDistinct, /* If not NULL, info on how to process DISTINCT */
  SelectDest *pDest,      /* How to dispose of the results */
  int iContinue,          /* Jump here to continue with next row */
  int iBreak              /* Jump here to break out of the inner loop */
){
  Vdbe *v = pParse->pVdbe;
................................................................................
  ** same value. However, if the results are being sent to the sorter, the
  ** values for any expressions that are also part of the sort-key are omitted
  ** from this array. In this case regOrig is set to zero.  */
  int regResult;              /* Start of memory holding current results */
  int regOrig;                /* Start of memory holding full result (or 0) */

  assert( v );
  assert( p->pEList!=0 );
  hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP;
  if( pSort && pSort->pOrderBy==0 ) pSort = 0;
  if( pSort==0 && !hasDistinct ){
    assert( iContinue!=0 );
    codeOffset(v, p->iOffset, iContinue);
  }

  /* Pull the requested columns.
  */
  nResultCol = p->pEList->nExpr;

  if( pDest->iSdst==0 ){
    if( pSort ){
      nPrefixReg = pSort->pOrderBy->nExpr;
      if( !(pSort->sortFlags & SORTFLAG_UseSorter) ) nPrefixReg++;
      pParse->nMem += nPrefixReg;
    }
................................................................................
    pParse->nMem += nResultCol;
  }
  pDest->nSdst = nResultCol;
  regOrig = regResult = pDest->iSdst;
  if( srcTab>=0 ){
    for(i=0; i<nResultCol; i++){
      sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
      VdbeComment((v, "%s", p->pEList->a[i].zName));
    }
  }else if( eDest!=SRT_Exists ){
    /* If the destination is an EXISTS(...) expression, the actual
    ** values returned by the SELECT are not required.
    */
    u8 ecelFlags;
    if( eDest==SRT_Mem || eDest==SRT_Output || eDest==SRT_Coroutine ){
      ecelFlags = SQLITE_ECEL_DUP;
    }else{
      ecelFlags = 0;
    }
    if( pSort && hasDistinct==0 && eDest!=SRT_EphemTab && eDest!=SRT_Table ){
      /* For each expression in p->pEList that is a copy of an expression in
      ** the ORDER BY clause (pSort->pOrderBy), set the associated 
      ** iOrderByCol value to one more than the index of the ORDER BY 
      ** expression within the sort-key that pushOntoSorter() will generate.
      ** This allows the p->pEList field to be omitted from the sorted record,
      ** saving space and CPU cycles.  */
      ecelFlags |= (SQLITE_ECEL_OMITREF|SQLITE_ECEL_REF);
      for(i=pSort->nOBSat; i<pSort->pOrderBy->nExpr; i++){
        int j;
        if( (j = pSort->pOrderBy->a[i].u.x.iOrderByCol)>0 ){
          p->pEList->a[j-1].u.x.iOrderByCol = i+1-pSort->nOBSat;
        }
      }
      regOrig = 0;
      assert( eDest==SRT_Set || eDest==SRT_Mem 
           || eDest==SRT_Coroutine || eDest==SRT_Output );
    }
    nResultCol = sqlite3ExprCodeExprList(pParse,p->pEList,regResult,0,ecelFlags);
  }

  /* If the DISTINCT keyword was present on the SELECT statement
  ** and this row has been seen before, then do not make this row
  ** part of the result.
  */
  if( hasDistinct ){
................................................................................
        pOp = sqlite3VdbeGetOp(v, pDistinct->addrTnct);
        pOp->opcode = OP_Null;
        pOp->p1 = 1;
        pOp->p2 = regPrev;

        iJump = sqlite3VdbeCurrentAddr(v) + nResultCol;
        for(i=0; i<nResultCol; i++){
          CollSeq *pColl = sqlite3ExprCollSeq(pParse, p->pEList->a[i].pExpr);
          if( i<nResultCol-1 ){
            sqlite3VdbeAddOp3(v, OP_Ne, regResult+i, iJump, regPrev+i);
            VdbeCoverage(v);
          }else{
            sqlite3VdbeAddOp3(v, OP_Eq, regResult+i, iContinue, regPrev+i);
            VdbeCoverage(v);
           }
................................................................................
    sqlite3VdbeAddOp2(v, OP_RowData, iQueue, regCurrent);
  }
  sqlite3VdbeAddOp1(v, OP_Delete, iQueue);

  /* Output the single row in Current */
  addrCont = sqlite3VdbeMakeLabel(v);
  codeOffset(v, regOffset, addrCont);
  selectInnerLoop(pParse, p, iCurrent,
      0, 0, pDest, addrCont, addrBreak);
  if( regLimit ){
    sqlite3VdbeAddOp2(v, OP_DecrJumpZero, regLimit, addrBreak);
    VdbeCoverage(v);
  }
  sqlite3VdbeResolveLabel(v, addrCont);

................................................................................
        int iCont, iBreak, iStart;
        assert( p->pEList );
        iBreak = sqlite3VdbeMakeLabel(v);
        iCont = sqlite3VdbeMakeLabel(v);
        computeLimitRegisters(pParse, p, iBreak);
        sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak); VdbeCoverage(v);
        iStart = sqlite3VdbeCurrentAddr(v);
        selectInnerLoop(pParse, p, unionTab,
                        0, 0, &dest, iCont, iBreak);
        sqlite3VdbeResolveLabel(v, iCont);
        sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart); VdbeCoverage(v);
        sqlite3VdbeResolveLabel(v, iBreak);
        sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0);
      }
      break;
................................................................................
      iCont = sqlite3VdbeMakeLabel(v);
      computeLimitRegisters(pParse, p, iBreak);
      sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak); VdbeCoverage(v);
      r1 = sqlite3GetTempReg(pParse);
      iStart = sqlite3VdbeAddOp2(v, OP_RowData, tab1, r1);
      sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0); VdbeCoverage(v);
      sqlite3ReleaseTempReg(pParse, r1);
      selectInnerLoop(pParse, p, tab1,
                      0, 0, &dest, iCont, iBreak);
      sqlite3VdbeResolveLabel(v, iCont);
      sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart); VdbeCoverage(v);
      sqlite3VdbeResolveLabel(v, iBreak);
      sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
      sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
      break;
................................................................................
    ** into an OP_Noop.
    */
    if( sSort.addrSortIndex>=0 && sSort.pOrderBy==0 ){
      sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex);
    }

    /* Use the standard inner loop. */
    assert( p->pEList==pEList );
    selectInnerLoop(pParse, p, -1, &sSort, &sDistinct, pDest,
                    sqlite3WhereContinueLabel(pWInfo),
                    sqlite3WhereBreakLabel(pWInfo));

    /* End the database scan loop.
    */
    sqlite3WhereEnd(pWInfo);
  }else{
................................................................................
      addrOutputRow = sqlite3VdbeCurrentAddr(v);
      sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
      VdbeCoverage(v);
      VdbeComment((v, "Groupby result generator entry point"));
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      finalizeAggFunctions(pParse, &sAggInfo);
      sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
      selectInnerLoop(pParse, p, -1, &sSort,
                      &sDistinct, pDest,
                      addrOutputRow+1, addrSetAbort);
      sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
      VdbeComment((v, "end groupby result generator"));

      /* Generate a subroutine that will reset the group-by accumulator
      */
................................................................................
        }
        sqlite3WhereEnd(pWInfo);
        finalizeAggFunctions(pParse, &sAggInfo);
      }

      sSort.pOrderBy = 0;
      sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
      selectInnerLoop(pParse, p, -1, 0, 0, 
                      pDest, addrEnd, addrEnd);
      sqlite3ExprListDelete(db, pDel);
    }
    sqlite3VdbeResolveLabel(v, addrEnd);
    
  } /* endif aggregate query */