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BitUtils: cleanup constexpr usage for msvc clz

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This commit is contained in:
Shawn Hoffman 2021-01-10 09:31:05 -08:00
parent 87debc6641
commit fc65f65891
1 changed files with 33 additions and 33 deletions
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62
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)); (T(-ExtractBit<0>(value)) >> (BitSize<T>() - left_shift_amount));
} }
// On some compiler / arch combinations, the compiler does not see instrinsics as constexpr, so mark template <typename T>
// the function as inline instead. constexpr int CountLeadingZerosConst(T value)
#if defined(_MSC_VER) && defined(_M_ARM_64) {
#define CONSTEXPR_FROM_INTRINSIC inline int result = sizeof(T) * 8;
#else while (value)
#define CONSTEXPR_FROM_INTRINSIC constexpr {
#endif result--;
value >>= 1;
}
return result;
}
CONSTEXPR_FROM_INTRINSIC constexpr int CountLeadingZeros(uint64_t value)
int CountLeadingZeros(uint64_t value)
{ {
#if defined(__GNUC__) #if defined(__GNUC__)
return value ? __builtin_clzll(value) : 64; return value ? __builtin_clzll(value) : 64;
#elif defined(_MSC_VER) && defined(_M_ARM_64) #elif defined(_MSC_VER)
return _CountLeadingZeros64(value); if (std::is_constant_evaluated())
#elif defined(_MSC_VER) && defined(_M_X86_64) {
return CountLeadingZerosConst(value);
}
else
{
unsigned long index = 0; unsigned long index = 0;
return _BitScanReverse64(&index, value) ? 63 - index : 64; return _BitScanReverse64(&index, value) ? 63 - index : 64;
#else
int result = 64;
while (value)
{
result--;
value >>= 1;
} }
return result; #else
return CountLeadingZerosConst(value);
#endif #endif
} }
CONSTEXPR_FROM_INTRINSIC constexpr int CountLeadingZeros(uint32_t value)
int CountLeadingZeros(uint32_t value)
{ {
#if defined(__GNUC__) #if defined(__GNUC__)
return value ? __builtin_clz(value) : 32; return value ? __builtin_clz(value) : 32;
#elif defined(_MSC_VER) && defined(_M_ARM_64) #elif defined(_MSC_VER)
return _CountLeadingZeros(value); if (std::is_constant_evaluated())
#elif defined(_MSC_VER) && defined(_M_X86_64) {
return CountLeadingZerosConst(value);
}
else
{
unsigned long index = 0; unsigned long index = 0;
return _BitScanReverse(&index, value) ? 31 - index : 32; return _BitScanReverse(&index, value) ? 31 - index : 32;
#else
int result = 32;
while (value)
{
result--;
value >>= 1;
} }
return result; #else
return CountLeadingZerosConst(value);
#endif #endif
} }