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Overview
Comment:Performance improvement and slight size reduction to the comparison operators in the VDBE.
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SHA1: 14052a7d088bed8196d90a3361ce717a5193bdc8
User & Date: drh 2014-09-17 23:37:39
Context
2014-09-18
01:21
Fix compiler warnings and change the nullMem structure initializer into a format that MSVC can understand. Closed-Leaf check-in: 163bfae8 user: drh tags: micro-optimizations
2014-09-17
23:37
Performance improvement and slight size reduction to the comparison operators in the VDBE. check-in: 14052a7d user: drh tags: micro-optimizations
16:41
In the Mem object, stop requiring that Mem.xDel be NULL when the MEM_Dyn bit is clear. Also reduce the amount of initialization of Mem objects. All for a small size reduction and performance increase. check-in: fdddb477 user: drh tags: micro-optimizations
Changes
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Changes to src/vdbe.c.

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    if( affinity ){
      applyAffinity(pIn1, affinity, encoding);
      applyAffinity(pIn3, affinity, encoding);
      if( db->mallocFailed ) goto no_mem;
    }

    assert( pOp->p4type==P4_COLLSEQ || pOp->p4.pColl==0 );

    ExpandBlob(pIn1);



    ExpandBlob(pIn3);


    res = sqlite3MemCompare(pIn3, pIn1, pOp->p4.pColl);
  }
  switch( pOp->opcode ){
    case OP_Eq:    res = res==0;     break;
    case OP_Ne:    res = res!=0;     break;
    case OP_Lt:    res = res<0;      break;
    case OP_Le:    res = res<=0;     break;
................................................................................
  }else{
    VdbeBranchTaken(res!=0, (pOp->p5 & SQLITE_NULLEQ)?2:3);
    if( res ){
      pc = pOp->p2-1;
    }
  }
  /* Undo any changes made by applyAffinity() to the input registers. */
  pIn1->flags = (pIn1->flags&~MEM_TypeMask) | (flags1&MEM_TypeMask);
  pIn3->flags = (pIn3->flags&~MEM_TypeMask) | (flags3&MEM_TypeMask);
  break;
}

/* Opcode: Permutation * * * P4 *
**
** Set the permutation used by the OP_Compare operator to be the array
** of integers in P4.







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    if( affinity ){
      applyAffinity(pIn1, affinity, encoding);
      applyAffinity(pIn3, affinity, encoding);
      if( db->mallocFailed ) goto no_mem;
    }

    assert( pOp->p4type==P4_COLLSEQ || pOp->p4.pColl==0 );
    if( pIn1->flags & MEM_Zero ){
      sqlite3VdbeMemExpandBlob(pIn1);
      flags1 &= ~MEM_Zero;
    }
    if( pIn3->flags & MEM_Zero ){
      sqlite3VdbeMemExpandBlob(pIn3);
      flags3 &= ~MEM_Zero;
    }
    res = sqlite3MemCompare(pIn3, pIn1, pOp->p4.pColl);
  }
  switch( pOp->opcode ){
    case OP_Eq:    res = res==0;     break;
    case OP_Ne:    res = res!=0;     break;
    case OP_Lt:    res = res<0;      break;
    case OP_Le:    res = res<=0;     break;
................................................................................
  }else{
    VdbeBranchTaken(res!=0, (pOp->p5 & SQLITE_NULLEQ)?2:3);
    if( res ){
      pc = pOp->p2-1;
    }
  }
  /* Undo any changes made by applyAffinity() to the input registers. */
  pIn1->flags = flags1;
  pIn3->flags = flags3;
  break;
}

/* Opcode: Permutation * * * P4 *
**
** Set the permutation used by the OP_Compare operator to be the array
** of integers in P4.