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Overview
Comment:Only use __builtin_bswap16() with GCC 4.8 and later.
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Timelines: family | ancestors | descendants | both | bswap-functions
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SHA1: ce8177e3e64d2ac4cd5d9e7757cdd5fcecd7d0ea
User & Date: drh 2015-06-30 14:01:20.529
Context
2015-06-30
15:10
Make use of built-in bswap32() and bswap16() functions in GCC/Clang for a significant performance improvement there. (check-in: 8bfcda3d10 user: drh tags: trunk)
14:01
Only use __builtin_bswap16() with GCC 4.8 and later. (Closed-Leaf check-in: ce8177e3e6 user: drh tags: bswap-functions)
13:28
Remove the use of htonl() in the previous check-in due to linkage issues. Add the get2byteAligned() macro and use it for access to the cell offsets on btree pages for about a 1% performance gain. (check-in: 79ff36b717 user: drh tags: bswap-functions)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/btreeInt.h.
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/*
** get2byteAligned(), unlike get2byte(), requires that its argument point to a
** two-byte aligned address.  get2bytea() is only used for accessing the
** cell addresses in a btree header.
*/
#if SQLITE_BYTEORDER==4321
# define get2byteAligned(x)  (*(u16*)(x))
#elif SQLITE_BYTEORDER==1234 && defined(__GNUC__)
# define get2byteAligned(x)  __builtin_bswap16(*(u16*)(x))
#else
# define get2byteAligned(x)  ((x)[0]<<8 | (x)[1])
#endif








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/*
** get2byteAligned(), unlike get2byte(), requires that its argument point to a
** two-byte aligned address.  get2bytea() is only used for accessing the
** cell addresses in a btree header.
*/
#if SQLITE_BYTEORDER==4321
# define get2byteAligned(x)  (*(u16*)(x))
#elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4008000
# define get2byteAligned(x)  __builtin_bswap16(*(u16*)(x))
#else
# define get2byteAligned(x)  ((x)[0]<<8 | (x)[1])
#endif
Changes to src/sqliteInt.h.
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#ifndef SQLITE_DISABLE_LFS
# define _LARGE_FILE       1
# ifndef _FILE_OFFSET_BITS
#   define _FILE_OFFSET_BITS 64
# endif
# define _LARGEFILE_SOURCE 1
#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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#ifndef SQLITE_DISABLE_LFS
# define _LARGE_FILE       1
# ifndef _FILE_OFFSET_BITS
#   define _FILE_OFFSET_BITS 64
# endif
# define _LARGEFILE_SOURCE 1
#endif

/* 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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