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Overview
Comment:Smaller and faster sqlite3IsNaN() implementation makes deserialization of floating point values much faster.
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SHA3-256: ea748edecb261f2b862d542daff6e99a6fd8879a8ace94b440d99e110577d1c1
User & Date: drh 2019-05-30 00:46:37
Context
2019-05-30
13:47
Optimization to the round() SQL function for large input values without a fractional part. check-in: e95138f5f4 user: drh tags: trunk
00:46
Smaller and faster sqlite3IsNaN() implementation makes deserialization of floating point values much faster. check-in: ea748edecb user: drh tags: trunk
2019-05-29
21:18
Much faster implementation of applyNumericAffinity() by avoiding some unnecessary calls to sqlite3Atoi64(). check-in: c1d8a3f654 user: drh tags: trunk
Changes
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Changes to src/sqliteInt.h.

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#if defined(SQLITE_ENABLE_MULTITHREADED_CHECKS) && !defined(SQLITE_MUTEX_OMIT)
void sqlite3MutexWarnOnContention(sqlite3_mutex*);
#else
# define sqlite3MutexWarnOnContention(x)
#endif

#ifndef SQLITE_OMIT_FLOATING_POINT



  int sqlite3IsNaN(double);
#else

# define sqlite3IsNaN(X)  0
#endif

/*
** An instance of the following structure holds information about SQL
** functions arguments that are the parameters to the printf() function.
*/







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#if defined(SQLITE_ENABLE_MULTITHREADED_CHECKS) && !defined(SQLITE_MUTEX_OMIT)
void sqlite3MutexWarnOnContention(sqlite3_mutex*);
#else
# define sqlite3MutexWarnOnContention(x)
#endif

#ifndef SQLITE_OMIT_FLOATING_POINT
# define EXP754 (((u64)0x7ff)<<52)
# define MAN754 ((((u64)1)<<52)-1)
# define IsNaN(X) (((X)&EXP754)==EXP754 && ((X)&MAN754)!=0)
  int sqlite3IsNaN(double);
#else
# define IsNaN(X)         0
# define sqlite3IsNaN(X)  0
#endif

/*
** An instance of the following structure holds information about SQL
** functions arguments that are the parameters to the printf() function.
*/

Changes to src/util.c.

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  return xCallback ? xCallback(iTest) : SQLITE_OK;
}
#endif

#ifndef SQLITE_OMIT_FLOATING_POINT
/*
** Return true if the floating point value is Not a Number (NaN).
**
** Use the math library isnan() function if compiled with SQLITE_HAVE_ISNAN.
** Otherwise, we have our own implementation that works on most systems.
*/
int sqlite3IsNaN(double x){
  int rc;   /* The value return */
#if !SQLITE_HAVE_ISNAN && !HAVE_ISNAN
  /*
  ** Systems that support the isnan() library function should probably
  ** make use of it by compiling with -DSQLITE_HAVE_ISNAN.  But we have
  ** found that many systems do not have a working isnan() function so
  ** this implementation is provided as an alternative.
  **
  ** This NaN test sometimes fails if compiled on GCC with -ffast-math.
  ** On the other hand, the use of -ffast-math comes with the following
  ** warning:
  **
  **      This option [-ffast-math] should never be turned on by any
  **      -O option since it can result in incorrect output for programs
  **      which depend on an exact implementation of IEEE or ISO 
  **      rules/specifications for math functions.
  **
  ** Under MSVC, this NaN test may fail if compiled with a floating-
  ** point precision mode other than /fp:precise.  From the MSDN 
  ** documentation:
  **
  **      The compiler [with /fp:precise] will properly handle comparisons 
  **      involving NaN. For example, x != x evaluates to true if x is NaN 
  **      ...
  */
#ifdef __FAST_MATH__
# error SQLite will not work correctly with the -ffast-math option of GCC.
#endif
  volatile double y = x;
  volatile double z = y;
  rc = (y!=z);
#else  /* if HAVE_ISNAN */
  rc = isnan(x);
#endif /* HAVE_ISNAN */
  testcase( rc );


  return rc;
}
#endif /* SQLITE_OMIT_FLOATING_POINT */

/*
** Compute a string length that is limited to what can be stored in
** lower 30 bits of a 32-bit signed integer.
**







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  return xCallback ? xCallback(iTest) : SQLITE_OK;
}
#endif

#ifndef SQLITE_OMIT_FLOATING_POINT
/*
** Return true if the floating point value is Not a Number (NaN).



*/
int sqlite3IsNaN(double x){



































  u64 y;
  memcpy(&y,&x,sizeof(y));
  return IsNaN(y);
}
#endif /* SQLITE_OMIT_FLOATING_POINT */

/*
** Compute a string length that is limited to what can be stored in
** lower 30 bits of a 32-bit signed integer.
**

Changes to src/vdbeaux.c.

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** and store the result in pMem.  Return the number of bytes read.
**
** This function is implemented as two separate routines for performance.
** The few cases that require local variables are broken out into a separate
** routine so that in most cases the overhead of moving the stack pointer
** is avoided.
*/ 
static u32 SQLITE_NOINLINE serialGet(
  const unsigned char *buf,     /* Buffer to deserialize from */
  u32 serial_type,              /* Serial type to deserialize */
  Mem *pMem                     /* Memory cell to write value into */
){
  u64 x = FOUR_BYTE_UINT(buf);
  u32 y = FOUR_BYTE_UINT(buf+4);
  x = (x<<32) + y;
................................................................................
    u64 t2 = t1;
    swapMixedEndianFloat(t2);
    assert( sizeof(r1)==sizeof(t2) && memcmp(&r1, &t2, sizeof(r1))==0 );
#endif
    assert( sizeof(x)==8 && sizeof(pMem->u.r)==8 );
    swapMixedEndianFloat(x);
    memcpy(&pMem->u.r, &x, sizeof(x));
    pMem->flags = sqlite3IsNaN(pMem->u.r) ? MEM_Null : MEM_Real;
  }
  return 8;
}
u32 sqlite3VdbeSerialGet(
  const unsigned char *buf,     /* Buffer to deserialize from */
  u32 serial_type,              /* Serial type to deserialize */
  Mem *pMem                     /* Memory cell to write value into */







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** and store the result in pMem.  Return the number of bytes read.
**
** This function is implemented as two separate routines for performance.
** The few cases that require local variables are broken out into a separate
** routine so that in most cases the overhead of moving the stack pointer
** is avoided.
*/ 
static u32 serialGet(
  const unsigned char *buf,     /* Buffer to deserialize from */
  u32 serial_type,              /* Serial type to deserialize */
  Mem *pMem                     /* Memory cell to write value into */
){
  u64 x = FOUR_BYTE_UINT(buf);
  u32 y = FOUR_BYTE_UINT(buf+4);
  x = (x<<32) + y;
................................................................................
    u64 t2 = t1;
    swapMixedEndianFloat(t2);
    assert( sizeof(r1)==sizeof(t2) && memcmp(&r1, &t2, sizeof(r1))==0 );
#endif
    assert( sizeof(x)==8 && sizeof(pMem->u.r)==8 );
    swapMixedEndianFloat(x);
    memcpy(&pMem->u.r, &x, sizeof(x));
    pMem->flags = IsNaN(x) ? MEM_Null : MEM_Real;
  }
  return 8;
}
u32 sqlite3VdbeSerialGet(
  const unsigned char *buf,     /* Buffer to deserialize from */
  u32 serial_type,              /* Serial type to deserialize */
  Mem *pMem                     /* Memory cell to write value into */