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Merge pull request #1017 from fanzeyi/fix-clang-cl-msvc

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fix clang-cl _tzcnt_u64 not defined issue
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Yann Collet 2021-08-09 12:58:58 -07:00 committed by GitHub
commit e78eeec86e
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1 changed files with 6 additions and 0 deletions
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6
lib/lz4.c
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@ -516,8 +516,14 @@ static unsigned LZ4_NbCommonBytes (reg_t val)
if (LZ4_isLittleEndian()) {
if (sizeof(val) == 8) {
# if defined(_MSC_VER) && (_MSC_VER >= 1800) && defined(_M_AMD64) && !defined(LZ4_FORCE_SW_BITCOUNT)
# if defined(__clang__) && (__clang_major__ < 10)
/* Avoid undefined clang-cl intrinics issue.
* See https://github.com/lz4/lz4/pull/1017 for details. */
return (unsigned)__builtin_ia32_tzcnt_u64(val) >> 3;
# else
/* x64 CPUS without BMI support interpret `TZCNT` as `REP BSF` */
return (unsigned)_tzcnt_u64(val) >> 3;
# endif
# elif defined(_MSC_VER) && defined(_WIN64) && !defined(LZ4_FORCE_SW_BITCOUNT)
unsigned long r = 0;
_BitScanForward64(&r, (U64)val);