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fix #820 : GCC v3.x 32-bits doesn't define 64-bits intrinsic

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resulting in undefined symbol error.
Push the requirement to GCC 4 for now.
Another solution, proposed by @NWilson, is to use __LONG_MAX__ instead.
__LONG_MAX__ is a GCC-specific constant, which value is supposed to depend on underlying target hardware (32/64 bits)
Might be better, but seems also more complex, hence more prone to side effects.
Keeping the simple solution for now (just rely on __GNUC__)
This commit is contained in:
Yann Collet 2017-09-11 15:17:31 -07:00
parent f325ee4e84
commit 3306bcb0e6
1 changed files with 2 additions and 2 deletions
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4
lib/compress/zstd_compress.h
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@ -168,7 +168,7 @@ static unsigned ZSTD_NbCommonBytes (register size_t val)
unsigned long r = 0; unsigned long r = 0;
_BitScanForward64( &r, (U64)val ); _BitScanForward64( &r, (U64)val );
return (unsigned)(r>>3); return (unsigned)(r>>3);
# elif defined(__GNUC__) && (__GNUC__ >= 3) # elif defined(__GNUC__) && (__GNUC__ >= 4)
return (__builtin_ctzll((U64)val) >> 3); return (__builtin_ctzll((U64)val) >> 3);
# else # else
static const int DeBruijnBytePos[64] = { 0, 0, 0, 0, 0, 1, 1, 2, static const int DeBruijnBytePos[64] = { 0, 0, 0, 0, 0, 1, 1, 2,
@ -202,7 +202,7 @@ static unsigned ZSTD_NbCommonBytes (register size_t val)
unsigned long r = 0; unsigned long r = 0;
_BitScanReverse64( &r, val ); _BitScanReverse64( &r, val );
return (unsigned)(r>>3); return (unsigned)(r>>3);
# elif defined(__GNUC__) && (__GNUC__ >= 3) # elif defined(__GNUC__) && (__GNUC__ >= 4)
return (__builtin_clzll(val) >> 3); return (__builtin_clzll(val) >> 3);
# else # else
unsigned r; unsigned r;