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Don't define the MSVC clz functions unless __builtin_clzll is unavailable.

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This is mainly just to avoid including intrin.h unnecessarily.
This commit is contained in:
Michael Winterberg 2016-01-07 15:19:27 -08:00
parent 28a303ddd4
commit b203beb61d
1 changed files with 16 additions and 21 deletions
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37
format.h
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@ -225,17 +225,16 @@ typedef __int64 intmax_t;
# define FMT_BUILTIN_CLZLL(n) __builtin_clzll(n)
#endif
#if defined(_MSC_VER)
# include <intrin.h> // _BitScanReverse, _BitScanReverse64
namespace fmt {
namespace internal {
// Some compilers masquerade as both MSVC and GCC-likes or
// otherwise support __builtin_clz and __builtin_clzll, so
// only define FMT_BUILTIN_CLZ using the MSVC intrinsics
// if the clz and clzll builtins are not available.
# if !defined(FMT_BUILTIN_CLZ)
# pragma intrinsic(_BitScanReverse)
#if defined(_MSC_VER) && !defined(FMT_BUILTIN_CLZLL)
# include <intrin.h> // _BitScanReverse, _BitScanReverse64
namespace fmt {
namespace internal {
# pragma intrinsic(_BitScanReverse)
inline uint32_t clz(uint32_t x) {
unsigned long r = 0;
_BitScanReverse(&r, x);
@ -244,40 +243,36 @@ inline uint32_t clz(uint32_t x) {
// Static analysis complains about using uninitialized data
// "r", but the only way that can happen is if "x" is 0,
// which the callers guarantee to not happen.
# pragma warning(suppress: 6102)
# pragma warning(suppress: 6102)
return 31 - r;
}
# define FMT_BUILTIN_CLZ(n) fmt::internal::clz(n)
# endif
# define FMT_BUILTIN_CLZ(n) fmt::internal::clz(n)
# if !defined(FMT_BUILTIN_CLZLL)
# pragma intrinsic(_BitScanReverse)
# ifdef _WIN64
# pragma intrinsic(_BitScanReverse64)
# endif
# ifdef _WIN64
# pragma intrinsic(_BitScanReverse64)
# endif
inline uint32_t clzll(uint64_t x) {
unsigned long r = 0;
# ifdef _WIN64
# ifdef _WIN64
_BitScanReverse64(&r, x);
# else
# else
// Scan the high 32 bits.
if (_BitScanReverse(&r, static_cast<uint32_t>(x >> 32)))
return 63 - (r + 32);
// Scan the low 32 bits.
_BitScanReverse(&r, static_cast<uint32_t>(x));
# endif
# endif
assert(x != 0);
// Static analysis complains about using uninitialized data
// "r", but the only way that can happen is if "x" is 0,
// which the callers guarantee to not happen.
# pragma warning(suppress: 6102)
# pragma warning(suppress: 6102)
return 63 - r;
}
# define FMT_BUILTIN_CLZLL(n) fmt::internal::clzll(n)
# endif
# define FMT_BUILTIN_CLZLL(n) fmt::internal::clzll(n)
}
}
#endif