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Don't initialize the first parameter of _BitScanForward* functions

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Like the document example, no need to initialize `r` to 0.
https://docs.microsoft.com/en-us/cpp/intrinsics/bitscanforward-bitscanforward64
This commit is contained in:
Ma Lin 2021-09-24 19:40:24 +08:00
parent 95f492ea17
commit e5ba858270
5 changed files with 10 additions and 12 deletions
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2
lib/common/entropy_common.c
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@ -43,7 +43,7 @@ static U32 FSE_ctz(U32 val)
assert(val != 0);
{
# if defined(_MSC_VER) /* Visual */
unsigned long r=0;
unsigned long r;
return _BitScanForward(&r, val) ? (unsigned)r : 0;
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* GCC Intrinsic */
return __builtin_ctz(val);

4
lib/common/zstd_internal.h
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@ -391,7 +391,7 @@ MEM_STATIC unsigned ZSTD_countTrailingZeros(size_t val)
# if STATIC_BMI2
return _tzcnt_u64(val);
# else
unsigned long r = 0;
unsigned long r;
return _BitScanForward64( &r, (U64)val ) ? (unsigned)(r >> 3) : 0;
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 4)
@ -409,7 +409,7 @@ MEM_STATIC unsigned ZSTD_countTrailingZeros(size_t val)
# endif
} else { /* 32 bits */
# if defined(_MSC_VER)
unsigned long r=0;
unsigned long r;
return _BitScanForward( &r, (U32)val ) ? (unsigned)(r >> 3) : 0;
# elif defined(__GNUC__) && (__GNUC__ >= 3)
return (__builtin_ctz((U32)val) >> 3);

4
lib/compress/zstd_compress_internal.h
View File

@ -672,7 +672,7 @@ static unsigned ZSTD_NbCommonBytes (size_t val)
# if STATIC_BMI2
return _tzcnt_u64(val) >> 3;
# else
unsigned long r = 0;
unsigned long r;
return _BitScanForward64( &r, (U64)val ) ? (unsigned)(r >> 3) : 0;
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 4)
@ -690,7 +690,7 @@ static unsigned ZSTD_NbCommonBytes (size_t val)
# endif
} else { /* 32 bits */
# if defined(_MSC_VER)
unsigned long r=0;
unsigned long r;
return _BitScanForward( &r, (U32)val ) ? (unsigned)(r >> 3) : 0;
# elif defined(__GNUC__) && (__GNUC__ >= 3)
return (__builtin_ctz((U32)val) >> 3);

2
lib/compress/zstd_lazy.c
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@ -882,7 +882,7 @@ static U32 ZSTD_VecMask_next(ZSTD_VecMask val) {
assert(val != 0);
# if defined(_MSC_VER) && defined(_WIN64)
{
unsigned long r = 0;
unsigned long r;
/* _BitScanForward64 is not defined outside of x64 */
return _BitScanForward64(&r, val) ? (U32)r : 0;
}

10
lib/dictBuilder/zdict.c
View File

@ -135,9 +135,8 @@ static unsigned ZDICT_NbCommonBytes (size_t val)
if (MEM_isLittleEndian()) {
if (MEM_64bits()) {
# if defined(_MSC_VER) && defined(_WIN64)
unsigned long r = 0;
_BitScanForward64( &r, (U64)val );
return (unsigned)(r>>3);
unsigned long r;
return _BitScanForward64(&r, (U64)val) ? (unsigned)(r >> 3) : 0;
# elif defined(__GNUC__) && (__GNUC__ >= 3)
return (unsigned)(__builtin_ctzll((U64)val) >> 3);
# else
@ -146,9 +145,8 @@ static unsigned ZDICT_NbCommonBytes (size_t val)
# endif
} else { /* 32 bits */
# if defined(_MSC_VER)
unsigned long r=0;
_BitScanForward( &r, (U32)val );
return (unsigned)(r>>3);
unsigned long r;
return _BitScanForward(&r, (U32)val) ? (unsigned)(r >> 3) : 0;
# elif defined(__GNUC__) && (__GNUC__ >= 3)
return (unsigned)(__builtin_ctz((U32)val) >> 3);
# else