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Restore De Bruijn algorithm for sparc64 where the compiler rely on a

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library function for __builtin_c?z.

Tested by:	Michael Moll <kvedulv kvedulv de>
This commit is contained in:
Xin LI 2013-02-13 17:30:54 +00:00
parent d902844bbd
commit 314caba11c
1 changed files with 63 additions and 0 deletions
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63
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/lz4.c
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@ -237,6 +237,16 @@ lz4_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
#define LZ4_FORCE_UNALIGNED_ACCESS 1
#endif
/*
* FreeBSD: can't use GCC's __builtin_ctz when using sparc64 because
* gcc currently rely on libcompiler_rt.
*
* TODO: revisit this when situation changes.
*/
#if defined(__sparc64__)
#define LZ4_FORCE_SW_BITCOUNT
#endif
/*
* Compiler Options
*/
@ -378,9 +388,38 @@ static inline int
LZ4_NbCommonBytes(register U64 val)
{
#if defined(LZ4_BIG_ENDIAN)
#if !defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_clzll(val) >> 3);
#else
int r;
if (!(val >> 32)) {
r = 4;
} else {
r = 0;
val >>= 32;
}
if (!(val >> 16)) {
r += 2;
val >>= 8;
} else {
val >>= 24;
}
r += (!val);
return (r);
#endif
#else
#if !defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_ctzll(val) >> 3);
#else
static const int DeBruijnBytePos[64] =
{ 0, 0, 0, 0, 0, 1, 1, 2, 0, 3, 1, 3, 1, 4, 2, 7, 0, 2, 3, 6, 1, 5,
3, 5, 1, 3, 4, 4, 2, 5, 6, 7, 7, 0, 1, 2, 3, 3, 4, 6, 2, 6, 5,
5, 3, 4, 5, 6, 7, 1, 2, 4, 6, 4,
4, 5, 7, 2, 6, 5, 7, 6, 7, 7
};
return DeBruijnBytePos[((U64) ((val & -val) * 0x0218A392CDABBD3F)) >>
58];
#endif
#endif
}
@ -390,9 +429,33 @@ static inline int
LZ4_NbCommonBytes(register U32 val)
{
#if defined(LZ4_BIG_ENDIAN)
#if !defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_clz(val) >> 3);
#else
int r;
if (!(val >> 16)) {
r = 2;
val >>= 8;
} else {
r = 0;
val >>= 24;
}
r += (!val);
return (r);
#endif
#else
#if !defined(LZ4_FORCE_SW_BITCOUNT)
return (__builtin_ctz(val) >> 3);
#else
static const int DeBruijnBytePos[32] = {
0, 0, 3, 0, 3, 1, 3, 0,
3, 2, 2, 1, 3, 2, 0, 1,
3, 3, 1, 2, 2, 2, 2, 0,
3, 1, 2, 0, 1, 0, 1, 1
};
return DeBruijnBytePos[((U32) ((val & -(S32) val) * 0x077CB531U)) >>
27];
#endif
#endif
}