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