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Overview
Comment:Simplification and performance improvements in sqlite3ExprDup() and its subroutines. More work is possible in this area.
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SHA1: 476cc2838824e0667e80ce527b9caa551dee4a77
User & Date: drh 2016-04-11 16:43:43
Context
2016-04-11
18:15
Performance optimizations in the column cache of the code generator, and especially the sqlite3ExprCacheRemove() routine. check-in: e35b345c user: drh tags: trunk
16:43
Simplification and performance improvements in sqlite3ExprDup() and its subroutines. More work is possible in this area. check-in: 476cc283 user: drh tags: trunk
16:35
Rename the OP_MX_JUMP macro to SQLITE_MX_JUMP_OPCODE to avoid confusing the opcode name generator. check-in: e554a4c3 user: drh tags: trunk
Changes
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Changes to src/expr.c.

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** to enforce this constraint.
*/
static int dupedExprStructSize(Expr *p, int flags){
  int nSize;
  assert( flags==EXPRDUP_REDUCE || flags==0 ); /* Only one flag value allowed */
  assert( EXPR_FULLSIZE<=0xfff );
  assert( (0xfff & (EP_Reduced|EP_TokenOnly))==0 );
  if( 0==(flags&EXPRDUP_REDUCE) ){
    nSize = EXPR_FULLSIZE;
  }else{
    assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
    assert( !ExprHasProperty(p, EP_FromJoin) ); 
    assert( !ExprHasProperty(p, EP_MemToken) );
    assert( !ExprHasProperty(p, EP_NoReduce) );
    if( p->pLeft || p->x.pList ){
................................................................................
** This function is similar to sqlite3ExprDup(), except that if pzBuffer 
** is not NULL then *pzBuffer is assumed to point to a buffer large enough 
** to store the copy of expression p, the copies of p->u.zToken
** (if applicable), and the copies of the p->pLeft and p->pRight expressions,
** if any. Before returning, *pzBuffer is set to the first byte past the
** portion of the buffer copied into by this function.
*/
static Expr *exprDup(sqlite3 *db, Expr *p, int flags, u8 **pzBuffer){
  Expr *pNew = 0;                      /* Value to return */
  assert( flags==0 || flags==EXPRDUP_REDUCE );


  assert( db!=0 );
  if( p ){
    const int isReduced = (flags&EXPRDUP_REDUCE);
    u8 *zAlloc;
    u32 staticFlag = 0;

    assert( pzBuffer==0 || isReduced );

    /* Figure out where to write the new Expr structure. */
    if( pzBuffer ){
      zAlloc = *pzBuffer;
      staticFlag = EP_Static;
    }else{
      zAlloc = sqlite3DbMallocRawNN(db, dupedExprSize(p, flags));

    }
    pNew = (Expr *)zAlloc;

    if( pNew ){
      /* Set nNewSize to the size allocated for the structure pointed to
      ** by pNew. This is either EXPR_FULLSIZE, EXPR_REDUCEDSIZE or
      ** EXPR_TOKENONLYSIZE. nToken is set to the number of bytes consumed
      ** by the copy of the p->u.zToken string (if any).
      */
      const unsigned nStructSize = dupedExprStructSize(p, flags);
      const int nNewSize = nStructSize & 0xfff;
      int nToken;
      if( !ExprHasProperty(p, EP_IntValue) && p->u.zToken ){
        nToken = sqlite3Strlen30(p->u.zToken) + 1;
      }else{
        nToken = 0;
      }
      if( isReduced ){
        assert( ExprHasProperty(p, EP_Reduced)==0 );
        memcpy(zAlloc, p, nNewSize);
      }else{
        u32 nSize = (u32)exprStructSize(p);
        memcpy(zAlloc, p, nSize);
        if( nSize<EXPR_FULLSIZE ){ 
          memset(&zAlloc[nSize], 0, EXPR_FULLSIZE-nSize);
        }
      }

      /* Set the EP_Reduced, EP_TokenOnly, and EP_Static flags appropriately. */
      pNew->flags &= ~(EP_Reduced|EP_TokenOnly|EP_Static|EP_MemToken);
      pNew->flags |= nStructSize & (EP_Reduced|EP_TokenOnly);
      pNew->flags |= staticFlag;

      /* Copy the p->u.zToken string, if any. */
      if( nToken ){
        char *zToken = pNew->u.zToken = (char*)&zAlloc[nNewSize];
        memcpy(zToken, p->u.zToken, nToken);
      }

      if( 0==((p->flags|pNew->flags) & EP_TokenOnly) ){
        /* Fill in the pNew->x.pSelect or pNew->x.pList member. */
        if( ExprHasProperty(p, EP_xIsSelect) ){
          pNew->x.pSelect = sqlite3SelectDup(db, p->x.pSelect, isReduced);
        }else{
          pNew->x.pList = sqlite3ExprListDup(db, p->x.pList, isReduced);
        }
      }

      /* Fill in pNew->pLeft and pNew->pRight. */
      if( ExprHasProperty(pNew, EP_Reduced|EP_TokenOnly) ){
        zAlloc += dupedExprNodeSize(p, flags);
        if( ExprHasProperty(pNew, EP_Reduced) ){

          pNew->pLeft = exprDup(db, p->pLeft, EXPRDUP_REDUCE, &zAlloc);

          pNew->pRight = exprDup(db, p->pRight, EXPRDUP_REDUCE, &zAlloc);
        }
        if( pzBuffer ){
          *pzBuffer = zAlloc;
        }
      }else{
        if( !ExprHasProperty(p, EP_TokenOnly) ){
          pNew->pLeft = sqlite3ExprDup(db, p->pLeft, 0);
          pNew->pRight = sqlite3ExprDup(db, p->pRight, 0);
        }
      }

    }
  }
  return pNew;
}

/*
** Create and return a deep copy of the object passed as the second 
................................................................................
** The flags parameter contains a combination of the EXPRDUP_XXX flags.
** If the EXPRDUP_REDUCE flag is set, then the structure returned is a
** truncated version of the usual Expr structure that will be stored as
** part of the in-memory representation of the database schema.
*/
Expr *sqlite3ExprDup(sqlite3 *db, Expr *p, int flags){
  assert( flags==0 || flags==EXPRDUP_REDUCE );
  return exprDup(db, p, flags, 0);
}
ExprList *sqlite3ExprListDup(sqlite3 *db, ExprList *p, int flags){
  ExprList *pNew;
  struct ExprList_item *pItem, *pOldItem;
  int i;
  assert( db!=0 );
  if( p==0 ) return 0;







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** to enforce this constraint.
*/
static int dupedExprStructSize(Expr *p, int flags){
  int nSize;
  assert( flags==EXPRDUP_REDUCE || flags==0 ); /* Only one flag value allowed */
  assert( EXPR_FULLSIZE<=0xfff );
  assert( (0xfff & (EP_Reduced|EP_TokenOnly))==0 );
  if( 0==flags ){
    nSize = EXPR_FULLSIZE;
  }else{
    assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
    assert( !ExprHasProperty(p, EP_FromJoin) ); 
    assert( !ExprHasProperty(p, EP_MemToken) );
    assert( !ExprHasProperty(p, EP_NoReduce) );
    if( p->pLeft || p->x.pList ){
................................................................................
** This function is similar to sqlite3ExprDup(), except that if pzBuffer 
** is not NULL then *pzBuffer is assumed to point to a buffer large enough 
** to store the copy of expression p, the copies of p->u.zToken
** (if applicable), and the copies of the p->pLeft and p->pRight expressions,
** if any. Before returning, *pzBuffer is set to the first byte past the
** portion of the buffer copied into by this function.
*/
static Expr *exprDup(sqlite3 *db, Expr *p, int dupFlags, u8 **pzBuffer){
  Expr *pNew;           /* Value to return */
  u8 *zAlloc;           /* Memory space from which to build Expr object */
  u32 staticFlag;       /* EP_Static if space not obtained from malloc */

  assert( db!=0 );
  assert( p );


  assert( dupFlags==0 || dupFlags==EXPRDUP_REDUCE );

  assert( pzBuffer==0 || dupFlags==EXPRDUP_REDUCE );

  /* Figure out where to write the new Expr structure. */
  if( pzBuffer ){
    zAlloc = *pzBuffer;
    staticFlag = EP_Static;
  }else{
    zAlloc = sqlite3DbMallocRawNN(db, dupedExprSize(p, dupFlags));
    staticFlag = 0;
  }
  pNew = (Expr *)zAlloc;

  if( pNew ){
    /* Set nNewSize to the size allocated for the structure pointed to
    ** by pNew. This is either EXPR_FULLSIZE, EXPR_REDUCEDSIZE or
    ** EXPR_TOKENONLYSIZE. nToken is set to the number of bytes consumed
    ** by the copy of the p->u.zToken string (if any).
    */
    const unsigned nStructSize = dupedExprStructSize(p, dupFlags);
    const int nNewSize = nStructSize & 0xfff;
    int nToken;
    if( !ExprHasProperty(p, EP_IntValue) && p->u.zToken ){
      nToken = sqlite3Strlen30(p->u.zToken) + 1;
    }else{
      nToken = 0;
    }
    if( dupFlags ){
      assert( ExprHasProperty(p, EP_Reduced)==0 );
      memcpy(zAlloc, p, nNewSize);
    }else{
      u32 nSize = (u32)exprStructSize(p);
      memcpy(zAlloc, p, nSize);
      if( nSize<EXPR_FULLSIZE ){ 
        memset(&zAlloc[nSize], 0, EXPR_FULLSIZE-nSize);
      }
    }

    /* Set the EP_Reduced, EP_TokenOnly, and EP_Static flags appropriately. */
    pNew->flags &= ~(EP_Reduced|EP_TokenOnly|EP_Static|EP_MemToken);
    pNew->flags |= nStructSize & (EP_Reduced|EP_TokenOnly);
    pNew->flags |= staticFlag;

    /* Copy the p->u.zToken string, if any. */
    if( nToken ){
      char *zToken = pNew->u.zToken = (char*)&zAlloc[nNewSize];
      memcpy(zToken, p->u.zToken, nToken);
    }

    if( 0==((p->flags|pNew->flags) & EP_TokenOnly) ){
      /* Fill in the pNew->x.pSelect or pNew->x.pList member. */
      if( ExprHasProperty(p, EP_xIsSelect) ){
        pNew->x.pSelect = sqlite3SelectDup(db, p->x.pSelect, dupFlags);
      }else{
        pNew->x.pList = sqlite3ExprListDup(db, p->x.pList, dupFlags);
      }
    }

    /* Fill in pNew->pLeft and pNew->pRight. */
    if( ExprHasProperty(pNew, EP_Reduced|EP_TokenOnly) ){
      zAlloc += dupedExprNodeSize(p, dupFlags);
      if( ExprHasProperty(pNew, EP_Reduced) ){
        pNew->pLeft = p->pLeft ?
                      exprDup(db, p->pLeft, EXPRDUP_REDUCE, &zAlloc) : 0;
        pNew->pRight = p->pRight ?
                       exprDup(db, p->pRight, EXPRDUP_REDUCE, &zAlloc) : 0;
      }
      if( pzBuffer ){
        *pzBuffer = zAlloc;
      }
    }else{
      if( !ExprHasProperty(p, EP_TokenOnly) ){
        pNew->pLeft = sqlite3ExprDup(db, p->pLeft, 0);
        pNew->pRight = sqlite3ExprDup(db, p->pRight, 0);
      }


    }
  }
  return pNew;
}

/*
** Create and return a deep copy of the object passed as the second 
................................................................................
** The flags parameter contains a combination of the EXPRDUP_XXX flags.
** If the EXPRDUP_REDUCE flag is set, then the structure returned is a
** truncated version of the usual Expr structure that will be stored as
** part of the in-memory representation of the database schema.
*/
Expr *sqlite3ExprDup(sqlite3 *db, Expr *p, int flags){
  assert( flags==0 || flags==EXPRDUP_REDUCE );
  return p ? exprDup(db, p, flags, 0) : 0;
}
ExprList *sqlite3ExprListDup(sqlite3 *db, ExprList *p, int flags){
  ExprList *pNew;
  struct ExprList_item *pItem, *pOldItem;
  int i;
  assert( db!=0 );
  if( p==0 ) return 0;