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Overview
Comment:Some optimization comments added to vdbe.c. No functional changes to code.
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SHA1:e7c22e3bffce63f3b47fa3683be8c00c42b2a7d3
User & Date: drh 2016-04-29 02:55:05
Context
2016-04-29
11:28
Lemon bug fix: Do not merge action routines unless their destructors are also identical. Problem and suggested fix reported on the mailing list by Kelvin Sherlock. check-in: 4792d6db user: drh tags: trunk
02:55
Some optimization comments added to vdbe.c. No functional changes to code. check-in: e7c22e3b user: drh tags: trunk
2016-04-28
22:29
Further simplifications and improved commentting on the rowset.c module, including several optimization comments. check-in: 9f15a520 user: drh tags: trunk
Changes
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Changes to src/vdbe.c.

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  int nByte;
  VdbeCursor *pCx = 0;
  nByte = 
      ROUND8(sizeof(VdbeCursor)) + 2*sizeof(u32)*nField + 
      (eCurType==CURTYPE_BTREE?sqlite3BtreeCursorSize():0);

  assert( iCur>=0 && iCur<p->nCursor );
  if( p->apCsr[iCur] ){
    sqlite3VdbeFreeCursor(p, p->apCsr[iCur]);
    p->apCsr[iCur] = 0;
  }
  if( SQLITE_OK==sqlite3VdbeMemClearAndResize(pMem, nByte) ){
    p->apCsr[iCur] = pCx = (VdbeCursor*)pMem->z;
    memset(pCx, 0, sizeof(VdbeCursor));
    pCx->eCurType = eCurType;
................................................................................
  Mem *pRec,          /* The value to apply affinity to */
  char affinity,      /* The affinity to be applied */
  u8 enc              /* Use this text encoding */
){
  if( affinity>=SQLITE_AFF_NUMERIC ){
    assert( affinity==SQLITE_AFF_INTEGER || affinity==SQLITE_AFF_REAL
             || affinity==SQLITE_AFF_NUMERIC );
    if( (pRec->flags & MEM_Int)==0 ){
      if( (pRec->flags & MEM_Real)==0 ){
        if( pRec->flags & MEM_Str ) applyNumericAffinity(pRec,1);
      }else{
        sqlite3VdbeIntegerAffinity(pRec);
      }
    }
  }else if( affinity==SQLITE_AFF_TEXT ){
    /* Only attempt the conversion to TEXT if there is an integer or real
    ** representation (blob and NULL do not get converted) but no string
    ** representation.
    */


    if( 0==(pRec->flags&MEM_Str) && (pRec->flags&(MEM_Real|MEM_Int)) ){
      sqlite3VdbeMemStringify(pRec, enc, 1);

    }
    pRec->flags &= ~(MEM_Real|MEM_Int);
  }
}

/*
** Try to convert the type of a function argument or a result column
................................................................................
}
static Mem *out2Prerelease(Vdbe *p, VdbeOp *pOp){
  Mem *pOut;
  assert( pOp->p2>0 );
  assert( pOp->p2<=(p->nMem+1 - p->nCursor) );
  pOut = &p->aMem[pOp->p2];
  memAboutToChange(p, pOut);
  if( VdbeMemDynamic(pOut) ){
    return out2PrereleaseWithClear(pOut);
  }else{
    pOut->flags = MEM_Int;
    return pOut;
  }
}








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  int nByte;
  VdbeCursor *pCx = 0;
  nByte = 
      ROUND8(sizeof(VdbeCursor)) + 2*sizeof(u32)*nField + 
      (eCurType==CURTYPE_BTREE?sqlite3BtreeCursorSize():0);

  assert( iCur>=0 && iCur<p->nCursor );
  if( p->apCsr[iCur] ){ /*OPTIMIZATION-IF-FALSE*/
    sqlite3VdbeFreeCursor(p, p->apCsr[iCur]);
    p->apCsr[iCur] = 0;
  }
  if( SQLITE_OK==sqlite3VdbeMemClearAndResize(pMem, nByte) ){
    p->apCsr[iCur] = pCx = (VdbeCursor*)pMem->z;
    memset(pCx, 0, sizeof(VdbeCursor));
    pCx->eCurType = eCurType;
................................................................................
  Mem *pRec,          /* The value to apply affinity to */
  char affinity,      /* The affinity to be applied */
  u8 enc              /* Use this text encoding */
){
  if( affinity>=SQLITE_AFF_NUMERIC ){
    assert( affinity==SQLITE_AFF_INTEGER || affinity==SQLITE_AFF_REAL
             || affinity==SQLITE_AFF_NUMERIC );
    if( (pRec->flags & MEM_Int)==0 ){ /*OPTIMIZATION-IF-FALSE*/
      if( (pRec->flags & MEM_Real)==0 ){
        if( pRec->flags & MEM_Str ) applyNumericAffinity(pRec,1);
      }else{
        sqlite3VdbeIntegerAffinity(pRec);
      }
    }
  }else if( affinity==SQLITE_AFF_TEXT ){
    /* Only attempt the conversion to TEXT if there is an integer or real
    ** representation (blob and NULL do not get converted) but no string
    ** representation.  It would be harmless to repeat the conversion if 
    ** there is already a string rep, but it is pointless to waste those
    ** CPU cycles. */
    if( 0==(pRec->flags&MEM_Str) ){ /*OPTIMIZATION-IF-FALSE*/
      if( (pRec->flags&(MEM_Real|MEM_Int)) ){
        sqlite3VdbeMemStringify(pRec, enc, 1);
      }
    }
    pRec->flags &= ~(MEM_Real|MEM_Int);
  }
}

/*
** Try to convert the type of a function argument or a result column
................................................................................
}
static Mem *out2Prerelease(Vdbe *p, VdbeOp *pOp){
  Mem *pOut;
  assert( pOp->p2>0 );
  assert( pOp->p2<=(p->nMem+1 - p->nCursor) );
  pOut = &p->aMem[pOp->p2];
  memAboutToChange(p, pOut);
  if( VdbeMemDynamic(pOut) ){ /*OPTIMIZATION-IF-FALSE*/
    return out2PrereleaseWithClear(pOut);
  }else{
    pOut->flags = MEM_Int;
    return pOut;
  }
}