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Comment:Use compiler intrinsic functions for signed integer math when overflow detection is needed.
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SHA1:d3ac32a6e7f1823450feb3d1089802542090d164
User & Date: drh 2017-01-03 21:57:11
Context
2017-01-04
04:18
Factor constant functions out of the inner loop since they are more expensive than the extra OP_Copy needed to move the result into place. check-in: 80ad317f user: drh tags: trunk
01:07
Attempt to factor out constant functions from the interior of table scans, since functions can often be expensive to compute. check-in: 62e9270a user: drh tags: factor-constant-funcs
00:26
Changes to the printf implementation for better performance. Closed-Leaf check-in: acdb8f6f user: drh tags: printf-optimization
2017-01-03
21:57
Use compiler intrinsic functions for signed integer math when overflow detection is needed. check-in: d3ac32a6 user: drh tags: trunk
21:50
Back out the use of __sync_fetch_and_sub() as it does not appear to work. Closed-Leaf check-in: 4c2efd42 user: drh tags: gnu-safe-math
14:45
Add the experimental affinity() SQL function when SQLITE_DEBUG is defined. check-in: bed0eaa5 user: drh tags: trunk
Changes
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Changes to src/sqliteInt.h.

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/* What version of GCC is being used.  0 means GCC is not being used */
#ifdef __GNUC__
# define GCC_VERSION (__GNUC__*1000000+__GNUC_MINOR__*1000+__GNUC_PATCHLEVEL__)
#else
# define GCC_VERSION 0
#endif









/* Needed for various definitions... */
#if defined(__GNUC__) && !defined(_GNU_SOURCE)
# define _GNU_SOURCE
#endif

#if defined(__OpenBSD__) && !defined(_BSD_SOURCE)







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/* What version of GCC is being used.  0 means GCC is not being used */
#ifdef __GNUC__
# define GCC_VERSION (__GNUC__*1000000+__GNUC_MINOR__*1000+__GNUC_PATCHLEVEL__)
#else
# define GCC_VERSION 0
#endif

/* What version of CLANG is being used.  0 means CLANG is not being used */
#ifdef __clang__
# define CLANG_VERSION \
            (__clang_major__*1000000+__clang_minor__*1000+__clang_patchlevel__)
#else
# define CLANG_VERSION 0
#endif

/* Needed for various definitions... */
#if defined(__GNUC__) && !defined(_GNU_SOURCE)
# define _GNU_SOURCE
#endif

#if defined(__OpenBSD__) && !defined(_BSD_SOURCE)

Changes to src/util.c.

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*/
u32 sqlite3Get4byte(const u8 *p){
#if SQLITE_BYTEORDER==4321
  u32 x;
  memcpy(&x,p,4);
  return x;
#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
    && defined(__GNUC__) && GCC_VERSION>=4003000
  u32 x;
  memcpy(&x,p,4);
  return __builtin_bswap32(x);
#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
    && defined(_MSC_VER) && _MSC_VER>=1300
  u32 x;
  memcpy(&x,p,4);
................................................................................
  return ((unsigned)p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
#endif
}
void sqlite3Put4byte(unsigned char *p, u32 v){
#if SQLITE_BYTEORDER==4321
  memcpy(p,&v,4);
#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
    && defined(__GNUC__) && GCC_VERSION>=4003000
  u32 x = __builtin_bswap32(v);
  memcpy(p,&x,4);
#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
    && defined(_MSC_VER) && _MSC_VER>=1300
  u32 x = _byteswap_ulong(v);
  memcpy(p,&x,4);
#else
................................................................................
/*
** Attempt to add, substract, or multiply the 64-bit signed value iB against
** the other 64-bit signed integer at *pA and store the result in *pA.
** Return 0 on success.  Or if the operation would have resulted in an
** overflow, leave *pA unchanged and return 1.
*/
int sqlite3AddInt64(i64 *pA, i64 iB){




  i64 iA = *pA;
  testcase( iA==0 ); testcase( iA==1 );
  testcase( iB==-1 ); testcase( iB==0 );
  if( iB>=0 ){
    testcase( iA>0 && LARGEST_INT64 - iA == iB );
    testcase( iA>0 && LARGEST_INT64 - iA == iB - 1 );
    if( iA>0 && LARGEST_INT64 - iA < iB ) return 1;
................................................................................
  }else{
    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 1 );
    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 2 );
    if( iA<0 && -(iA + LARGEST_INT64) > iB + 1 ) return 1;
  }
  *pA += iB;
  return 0; 

}
int sqlite3SubInt64(i64 *pA, i64 iB){




  testcase( iB==SMALLEST_INT64+1 );
  if( iB==SMALLEST_INT64 ){
    testcase( (*pA)==(-1) ); testcase( (*pA)==0 );
    if( (*pA)>=0 ) return 1;
    *pA -= iB;
    return 0;
  }else{
    return sqlite3AddInt64(pA, -iB);
  }

}
int sqlite3MulInt64(i64 *pA, i64 iB){




  i64 iA = *pA;
  if( iB>0 ){
    if( iA>LARGEST_INT64/iB ) return 1;
    if( iA<SMALLEST_INT64/iB ) return 1;
  }else if( iB<0 ){
    if( iA>0 ){
      if( iB<SMALLEST_INT64/iA ) return 1;
................................................................................
      if( iB==SMALLEST_INT64 ) return 1;
      if( iA==SMALLEST_INT64 ) return 1;
      if( -iA>LARGEST_INT64/-iB ) return 1;
    }
  }
  *pA = iA*iB;
  return 0;

}

/*
** Compute the absolute value of a 32-bit signed integer, of possible.  Or 
** if the integer has a value of -2147483648, return +2147483647
*/
int sqlite3AbsInt32(int x){







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*/
u32 sqlite3Get4byte(const u8 *p){
#if SQLITE_BYTEORDER==4321
  u32 x;
  memcpy(&x,p,4);
  return x;
#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
    && (GCC_VERSION>=4003000 || CLANG_VERSION>=3000000)
  u32 x;
  memcpy(&x,p,4);
  return __builtin_bswap32(x);
#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
    && defined(_MSC_VER) && _MSC_VER>=1300
  u32 x;
  memcpy(&x,p,4);
................................................................................
  return ((unsigned)p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
#endif
}
void sqlite3Put4byte(unsigned char *p, u32 v){
#if SQLITE_BYTEORDER==4321
  memcpy(p,&v,4);
#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
    && (GCC_VERSION>=4003000 || CLANG_VERSION>=3000000)
  u32 x = __builtin_bswap32(v);
  memcpy(p,&x,4);
#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
    && defined(_MSC_VER) && _MSC_VER>=1300
  u32 x = _byteswap_ulong(v);
  memcpy(p,&x,4);
#else
................................................................................
/*
** Attempt to add, substract, or multiply the 64-bit signed value iB against
** the other 64-bit signed integer at *pA and store the result in *pA.
** Return 0 on success.  Or if the operation would have resulted in an
** overflow, leave *pA unchanged and return 1.
*/
int sqlite3AddInt64(i64 *pA, i64 iB){
#if !defined(SQLITE_DISABLE_INTRINSIC) \
    && (GCC_VERSION>=5004000 || CLANG_VERSION>=4000000)
  return __builtin_add_overflow(*pA, iB, pA);
#else
  i64 iA = *pA;
  testcase( iA==0 ); testcase( iA==1 );
  testcase( iB==-1 ); testcase( iB==0 );
  if( iB>=0 ){
    testcase( iA>0 && LARGEST_INT64 - iA == iB );
    testcase( iA>0 && LARGEST_INT64 - iA == iB - 1 );
    if( iA>0 && LARGEST_INT64 - iA < iB ) return 1;
................................................................................
  }else{
    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 1 );
    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 2 );
    if( iA<0 && -(iA + LARGEST_INT64) > iB + 1 ) return 1;
  }
  *pA += iB;
  return 0; 
#endif
}
int sqlite3SubInt64(i64 *pA, i64 iB){
#if !defined(SQLITE_DISABLE_INTRINSIC) \
    && (GCC_VERSION>=5004000 || CLANG_VERSION>=4000000)
  return __builtin_sub_overflow(*pA, iB, pA);
#else
  testcase( iB==SMALLEST_INT64+1 );
  if( iB==SMALLEST_INT64 ){
    testcase( (*pA)==(-1) ); testcase( (*pA)==0 );
    if( (*pA)>=0 ) return 1;
    *pA -= iB;
    return 0;
  }else{
    return sqlite3AddInt64(pA, -iB);
  }
#endif
}
int sqlite3MulInt64(i64 *pA, i64 iB){
#if !defined(SQLITE_DISABLE_INTRINSIC) \
    && (GCC_VERSION>=5004000 || CLANG_VERSION>=4000000)
  return __builtin_mul_overflow(*pA, iB, pA);
#else
  i64 iA = *pA;
  if( iB>0 ){
    if( iA>LARGEST_INT64/iB ) return 1;
    if( iA<SMALLEST_INT64/iB ) return 1;
  }else if( iB<0 ){
    if( iA>0 ){
      if( iB<SMALLEST_INT64/iA ) return 1;
................................................................................
      if( iB==SMALLEST_INT64 ) return 1;
      if( iA==SMALLEST_INT64 ) return 1;
      if( -iA>LARGEST_INT64/-iB ) return 1;
    }
  }
  *pA = iA*iB;
  return 0;
#endif
}

/*
** Compute the absolute value of a 32-bit signed integer, of possible.  Or 
** if the integer has a value of -2147483648, return +2147483647
*/
int sqlite3AbsInt32(int x){