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Comment:Avoid unnecessary Mem initializations when generating a new sqlite3_stmt object.
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SHA1: 47ae1cda8dc255d100aeb8cb90ea4c9e449509be
User & Date: drh 2016-09-30 17:46:44
Context
2016-09-30
18:35
Remove unnecessary fields from the Parse object. check-in: 814e41da user: drh tags: trunk
17:46
Avoid unnecessary Mem initializations when generating a new sqlite3_stmt object. check-in: 47ae1cda user: drh tags: trunk
2016-09-29
20:28
Small size and performance optimization to sqlite3VdbeChangeP5(). check-in: 3c93c8f5 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/vdbe.c.

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case OP_Null: {           /* out2 */
  int cnt;
  u16 nullFlag;
  pOut = out2Prerelease(p, pOp);
  cnt = pOp->p3-pOp->p2;
  assert( pOp->p3<=(p->nMem+1 - p->nCursor) );
  pOut->flags = nullFlag = pOp->p1 ? (MEM_Null|MEM_Cleared) : MEM_Null;

  while( cnt>0 ){
    pOut++;
    memAboutToChange(p, pOut);
    sqlite3VdbeMemSetNull(pOut);
    pOut->flags = nullFlag;

    cnt--;
  }
  break;
}

/* Opcode: SoftNull P1 * * * *
** Synopsis: r[P1]=NULL







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case OP_Null: {           /* out2 */
  int cnt;
  u16 nullFlag;
  pOut = out2Prerelease(p, pOp);
  cnt = pOp->p3-pOp->p2;
  assert( pOp->p3<=(p->nMem+1 - p->nCursor) );
  pOut->flags = nullFlag = pOp->p1 ? (MEM_Null|MEM_Cleared) : MEM_Null;
  pOut->n = 0;
  while( cnt>0 ){
    pOut++;
    memAboutToChange(p, pOut);
    sqlite3VdbeMemSetNull(pOut);
    pOut->flags = nullFlag;
    pOut->n = 0;
    cnt--;
  }
  break;
}

/* Opcode: SoftNull P1 * * * *
** Synopsis: r[P1]=NULL

Changes to src/vdbeaux.c.

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  fprintf(pOut, zFormat1, pc, 
      sqlite3OpcodeName(pOp->opcode), pOp->p1, pOp->p2, pOp->p3, zP4, pOp->p5,
      zCom
  );
  fflush(pOut);
}
#endif
















/*
** Release an array of N Mem elements
*/
static void releaseMemArray(Mem *p, int N){
  if( p && N ){
    Mem *pEnd = &p[N];
................................................................................
    if( sqlite3VdbeMemClearAndResize(pMem, 100) ){ /* P4 */
      assert( p->db->mallocFailed );
      return SQLITE_ERROR;
    }
    pMem->flags = MEM_Str|MEM_Term;
    zP4 = displayP4(pOp, pMem->z, pMem->szMalloc);
    if( zP4!=pMem->z ){

      sqlite3VdbeMemSetStr(pMem, zP4, -1, SQLITE_UTF8, 0);
    }else{
      assert( pMem->z!=0 );
      pMem->n = sqlite3Strlen30(pMem->z);
      pMem->enc = SQLITE_UTF8;
    }
    pMem++;
................................................................................
  ** of the prepared statement.
  */
  n = ROUND8(sizeof(Op)*p->nOp);              /* Bytes of opcode memory used */
  x.pSpace = &((u8*)p->aOp)[n];               /* Unused opcode memory */
  assert( EIGHT_BYTE_ALIGNMENT(x.pSpace) );
  x.nFree = ROUNDDOWN8(pParse->szOpAlloc - n);  /* Bytes of unused memory */
  assert( x.nFree>=0 );
  if( x.nFree>0 ){
    memset(x.pSpace, 0, x.nFree);
    assert( EIGHT_BYTE_ALIGNMENT(&x.pSpace[x.nFree]) );
  }

  resolveP2Values(p, &nArg);
  p->usesStmtJournal = (u8)(pParse->isMultiWrite && pParse->mayAbort);
  if( pParse->explain && nMem<10 ){
    nMem = 10;
  }
  p->expired = 0;
................................................................................
    p->aVar = allocSpace(&x, p->aVar, nVar*sizeof(Mem));
    p->apArg = allocSpace(&x, p->apArg, nArg*sizeof(Mem*));
    p->apCsr = allocSpace(&x, p->apCsr, nCursor*sizeof(VdbeCursor*));
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
    p->anExec = allocSpace(&x, p->anExec, p->nOp*sizeof(i64));
#endif
    if( x.nNeeded==0 ) break;
    x.pSpace = p->pFree = sqlite3DbMallocZero(db, x.nNeeded);
    x.nFree = x.nNeeded;
  }while( !db->mallocFailed );

  p->nCursor = nCursor;
  if( p->aVar ){
    p->nVar = (ynVar)nVar;
    for(n=0; n<nVar; n++){
      p->aVar[n].flags = MEM_Null;
      p->aVar[n].db = db;
    }
  }
  p->nzVar = pParse->nzVar;
  p->azVar = pParse->azVar;
  pParse->nzVar =  0;
  pParse->azVar = 0;
  if( p->aMem ){




    p->nMem = nMem;
    for(n=0; n<nMem; n++){
      p->aMem[n].flags = MEM_Undefined;
      p->aMem[n].db = db;






    }
  }
  p->explain = pParse->explain;
  sqlite3VdbeRewind(p);
}

/*
** Close a VDBE cursor and release all the resources that cursor 
** happens to hold.
*/
................................................................................
  int n;
  sqlite3 *db = p->db;

  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
  sqlite3DbFree(db, p->aColName);
  n = nResColumn*COLNAME_N;
  p->nResColumn = (u16)nResColumn;
  p->aColName = pColName = (Mem*)sqlite3DbMallocZero(db, sizeof(Mem)*n );
  if( p->aColName==0 ) return;
  while( n-- > 0 ){
    pColName->flags = MEM_Null;
    pColName->db = p->db;
    pColName++;
  }
}

/*
** Set the name of the idx'th column to be returned by the SQL statement.
** zName must be a pointer to a nul terminated string.
**
** This call must be made after a call to sqlite3VdbeSetNumCols().







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  fprintf(pOut, zFormat1, pc, 
      sqlite3OpcodeName(pOp->opcode), pOp->p1, pOp->p2, pOp->p3, zP4, pOp->p5,
      zCom
  );
  fflush(pOut);
}
#endif

/*
** Initialize an array of N Mem element.
*/
static void initMemArray(Mem *p, int N, sqlite3 *db, u16 flags){
  while( (N--)>0 ){
    p->db = db;
    p->flags = flags;
    p->szMalloc = 0;
#ifdef SQLITE_DEBUG
    p->pScopyFrom = 0;
#endif
    p++;
  }
}

/*
** Release an array of N Mem elements
*/
static void releaseMemArray(Mem *p, int N){
  if( p && N ){
    Mem *pEnd = &p[N];
................................................................................
    if( sqlite3VdbeMemClearAndResize(pMem, 100) ){ /* P4 */
      assert( p->db->mallocFailed );
      return SQLITE_ERROR;
    }
    pMem->flags = MEM_Str|MEM_Term;
    zP4 = displayP4(pOp, pMem->z, pMem->szMalloc);
    if( zP4!=pMem->z ){
      pMem->n = 0;
      sqlite3VdbeMemSetStr(pMem, zP4, -1, SQLITE_UTF8, 0);
    }else{
      assert( pMem->z!=0 );
      pMem->n = sqlite3Strlen30(pMem->z);
      pMem->enc = SQLITE_UTF8;
    }
    pMem++;
................................................................................
  ** of the prepared statement.
  */
  n = ROUND8(sizeof(Op)*p->nOp);              /* Bytes of opcode memory used */
  x.pSpace = &((u8*)p->aOp)[n];               /* Unused opcode memory */
  assert( EIGHT_BYTE_ALIGNMENT(x.pSpace) );
  x.nFree = ROUNDDOWN8(pParse->szOpAlloc - n);  /* Bytes of unused memory */
  assert( x.nFree>=0 );


  assert( EIGHT_BYTE_ALIGNMENT(&x.pSpace[x.nFree]) );


  resolveP2Values(p, &nArg);
  p->usesStmtJournal = (u8)(pParse->isMultiWrite && pParse->mayAbort);
  if( pParse->explain && nMem<10 ){
    nMem = 10;
  }
  p->expired = 0;
................................................................................
    p->aVar = allocSpace(&x, p->aVar, nVar*sizeof(Mem));
    p->apArg = allocSpace(&x, p->apArg, nArg*sizeof(Mem*));
    p->apCsr = allocSpace(&x, p->apCsr, nCursor*sizeof(VdbeCursor*));
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
    p->anExec = allocSpace(&x, p->anExec, p->nOp*sizeof(i64));
#endif
    if( x.nNeeded==0 ) break;
    x.pSpace = p->pFree = sqlite3DbMallocRawNN(db, x.nNeeded);
    x.nFree = x.nNeeded;
  }while( !db->mallocFailed );









  p->nzVar = pParse->nzVar;
  p->azVar = pParse->azVar;
  pParse->nzVar =  0;
  pParse->azVar = 0;
  p->explain = pParse->explain;
  if( db->mallocFailed==0 ){
    p->nCursor = nCursor;
    p->nVar = (ynVar)nVar;
    initMemArray(p->aVar, nVar, db, MEM_Null);
    p->nMem = nMem;



    initMemArray(p->aMem, nMem, db, MEM_Undefined);
    memset(p->apArg, 0, nArg*sizeof(Mem*));
    memset(p->apCsr, 0, nCursor*sizeof(VdbeCursor*));
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
    memset(p->anExec, 0, p->nOp*sizeof(i64));
#endif
  }


  sqlite3VdbeRewind(p);
}

/*
** Close a VDBE cursor and release all the resources that cursor 
** happens to hold.
*/
................................................................................
  int n;
  sqlite3 *db = p->db;

  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
  sqlite3DbFree(db, p->aColName);
  n = nResColumn*COLNAME_N;
  p->nResColumn = (u16)nResColumn;
  p->aColName = pColName = (Mem*)sqlite3DbMallocRawNN(db, sizeof(Mem)*n );
  if( p->aColName==0 ) return;
  initMemArray(p->aColName, n, p->db, MEM_Null);




}

/*
** Set the name of the idx'th column to be returned by the SQL statement.
** zName must be a pointer to a nul terminated string.
**
** This call must be made after a call to sqlite3VdbeSetNumCols().

Changes to src/vdbemem.c.

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  assert( !(fg&(MEM_Str|MEM_Blob)) );
  assert( fg&(MEM_Int|MEM_Real) );
  assert( (pMem->flags&MEM_RowSet)==0 );
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );


  if( sqlite3VdbeMemClearAndResize(pMem, nByte) ){

    return SQLITE_NOMEM_BKPT;
  }

  /* For a Real or Integer, use sqlite3_snprintf() to produce the UTF-8
  ** string representation of the value. Then, if the required encoding
  ** is UTF-16le or UTF-16be do a translation.
  ** 







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  assert( !(fg&(MEM_Str|MEM_Blob)) );
  assert( fg&(MEM_Int|MEM_Real) );
  assert( (pMem->flags&MEM_RowSet)==0 );
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );


  if( sqlite3VdbeMemClearAndResize(pMem, nByte) ){
    pMem->enc = 0;
    return SQLITE_NOMEM_BKPT;
  }

  /* For a Real or Integer, use sqlite3_snprintf() to produce the UTF-8
  ** string representation of the value. Then, if the required encoding
  ** is UTF-16le or UTF-16be do a translation.
  **