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Merge pull request #9435 from shuffle2/constexpr-error 

BitUtils: cleanup constexpr usage for msvc clz
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LC 2021-01-10 14:58:20 -05:00 committed by GitHub
parent 87debc6641 fc65f65891
commit 79a234eff7
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1 changed files with 33 additions and 33 deletions
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66
Source/Core/Common/BitUtils.h
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@ -362,53 +362,53 @@ T ExpandValue(T value, size_t left_shift_amount)
(T(-ExtractBit<0>(value)) >> (BitSize<T>() - left_shift_amount));
}
// On some compiler / arch combinations, the compiler does not see instrinsics as constexpr, so mark
// the function as inline instead.
#if defined(_MSC_VER) && defined(_M_ARM_64)
#define CONSTEXPR_FROM_INTRINSIC inline
#else
#define CONSTEXPR_FROM_INTRINSIC constexpr
#endif
template <typename T>
constexpr int CountLeadingZerosConst(T value)
{
int result = sizeof(T) * 8;
while (value)
{
result--;
value >>= 1;
}
return result;
}
CONSTEXPR_FROM_INTRINSIC
int CountLeadingZeros(uint64_t value)
constexpr int CountLeadingZeros(uint64_t value)
{
#if defined(__GNUC__)
return value ? __builtin_clzll(value) : 64;
#elif defined(_MSC_VER) && defined(_M_ARM_64)
return _CountLeadingZeros64(value);
#elif defined(_MSC_VER) && defined(_M_X86_64)
unsigned long index = 0;
return _BitScanReverse64(&index, value) ? 63 - index : 64;
#else
int result = 64;
while (value)
#elif defined(_MSC_VER)
if (std::is_constant_evaluated())
{
result--;
value >>= 1;
return CountLeadingZerosConst(value);
}
return result;
else
{
unsigned long index = 0;
return _BitScanReverse64(&index, value) ? 63 - index : 64;
}
#else
return CountLeadingZerosConst(value);
#endif
}
CONSTEXPR_FROM_INTRINSIC
int CountLeadingZeros(uint32_t value)
constexpr int CountLeadingZeros(uint32_t value)
{
#if defined(__GNUC__)
return value ? __builtin_clz(value) : 32;
#elif defined(_MSC_VER) && defined(_M_ARM_64)
return _CountLeadingZeros(value);
#elif defined(_MSC_VER) && defined(_M_X86_64)
unsigned long index = 0;
return _BitScanReverse(&index, value) ? 31 - index : 32;
#else
int result = 32;
while (value)
#elif defined(_MSC_VER)
if (std::is_constant_evaluated())
{
result--;
value >>= 1;
return CountLeadingZerosConst(value);
}
return result;
else
{
unsigned long index = 0;
return _BitScanReverse(&index, value) ? 31 - index : 32;
}
#else
return CountLeadingZerosConst(value);
#endif
}