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Overview
Comment:Work around a problem with GCC on 32-bit machines that cause the CAST operator to generate a floating-point result for strings that could be represented as very large integers.
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SHA3-256:1b02731962c21bb097a88801ece76ff441bf882519a821a246da84f4e2a33455
User & Date: drh 2018-01-23 17:33:42
Context
2018-01-23
19:24
Remove an unreachable branch from sqlite3SkipAccumulatorLoad(). check-in: 8b9c8eab user: drh tags: trunk
17:33
Work around a problem with GCC on 32-bit machines that cause the CAST operator to generate a floating-point result for strings that could be represented as very large integers. check-in: 1b027319 user: drh tags: trunk
16:38
Fix a bug causing spurious "sub-select returns N columns expected 1" errors in join queries with a term like "(a, b) IN (SELECT ...)" in the WHERE clause. Ticket [7310e2fb3d046a5f5]. check-in: 14dfd96f user: dan tags: trunk
Changes
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Changes to src/vdbemem.c.

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  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );

  pMem->u.r = sqlite3VdbeRealValue(pMem);
  MemSetTypeFlag(pMem, MEM_Real);
  return SQLITE_OK;
}













/*
** Convert pMem so that it has types MEM_Real or MEM_Int or both.
** Invalidate any prior representations.
**
** Every effort is made to force the conversion, even if the input
** is a string that does not look completely like a number.  Convert
................................................................................
    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
    rc = sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc);
    if( rc==0 ){
      MemSetTypeFlag(pMem, MEM_Int);
    }else{
      i64 i = pMem->u.i;
      sqlite3AtoF(pMem->z, &pMem->u.r, pMem->n, pMem->enc);
      if( rc==1 && pMem->u.r==(double)i ){
        pMem->u.i = i;
        MemSetTypeFlag(pMem, MEM_Int);
      }else{
        MemSetTypeFlag(pMem, MEM_Real);
      }
    }
  }







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  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );

  pMem->u.r = sqlite3VdbeRealValue(pMem);
  MemSetTypeFlag(pMem, MEM_Real);
  return SQLITE_OK;
}

/* Compare a floating point value to an integer.  Return true if the two
** values are the same within the precision of the floating point value.
**
** For some versions of GCC on 32-bit machines, if you do the more obvious
** comparison of "r1==(double)i" you sometimes get an answer of false even
** though the r1 and (double)i values are bit-for-bit the same.
*/
static int sqlite3RealSameAsInt(double r1, sqlite3_int64 i){
  double r2 = (double)i;
  return memcmp(&r1, &r2, sizeof(r1))==0;
}

/*
** Convert pMem so that it has types MEM_Real or MEM_Int or both.
** Invalidate any prior representations.
**
** Every effort is made to force the conversion, even if the input
** is a string that does not look completely like a number.  Convert
................................................................................
    assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
    rc = sqlite3Atoi64(pMem->z, &pMem->u.i, pMem->n, pMem->enc);
    if( rc==0 ){
      MemSetTypeFlag(pMem, MEM_Int);
    }else{
      i64 i = pMem->u.i;
      sqlite3AtoF(pMem->z, &pMem->u.r, pMem->n, pMem->enc);
      if( rc==1 && sqlite3RealSameAsInt(pMem->u.r, i) ){
        pMem->u.i = i;
        MemSetTypeFlag(pMem, MEM_Int);
      }else{
        MemSetTypeFlag(pMem, MEM_Real);
      }
    }
  }