diff options
Diffstat (limited to 'runtime/base/bit_utils.h')
| -rw-r--r-- | runtime/base/bit_utils.h | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/runtime/base/bit_utils.h b/runtime/base/bit_utils.h index 34cddbff6a..d2a99f1a39 100644 --- a/runtime/base/bit_utils.h +++ b/runtime/base/bit_utils.h @@ -46,10 +46,14 @@ template<typename T> constexpr int CLZ(T x) { static_assert(std::is_integral<T>::value, "T must be integral"); static_assert(std::is_unsigned<T>::value, "T must be unsigned"); - static_assert(sizeof(T) <= sizeof(long long), // NOLINT [runtime/int] [4] - "T too large, must be smaller than long long"); + static_assert(std::numeric_limits<T>::radix == 2, "Unexpected radix!"); + static_assert(sizeof(T) == sizeof(uint64_t) || sizeof(T) <= sizeof(uint32_t), + "Unsupported sizeof(T)"); DCHECK_NE(x, 0u); - return (sizeof(T) == sizeof(uint32_t)) ? __builtin_clz(x) : __builtin_clzll(x); + constexpr bool is_64_bit = (sizeof(T) == sizeof(uint64_t)); + constexpr size_t adjustment = + is_64_bit ? 0u : std::numeric_limits<uint32_t>::digits - std::numeric_limits<T>::digits; + return is_64_bit ? __builtin_clzll(x) : __builtin_clz(x) - adjustment; } // Similar to CLZ except that on zero input it returns bitwidth and supports signed integers. @@ -65,10 +69,10 @@ constexpr int CTZ(T x) { static_assert(std::is_integral<T>::value, "T must be integral"); // It is not unreasonable to ask for trailing zeros in a negative number. As such, do not check // that T is an unsigned type. - static_assert(sizeof(T) <= sizeof(long long), // NOLINT [runtime/int] [4] - "T too large, must be smaller than long long"); + static_assert(sizeof(T) == sizeof(uint64_t) || sizeof(T) <= sizeof(uint32_t), + "Unsupported sizeof(T)"); DCHECK_NE(x, static_cast<T>(0)); - return (sizeof(T) == sizeof(uint32_t)) ? __builtin_ctz(x) : __builtin_ctzll(x); + return (sizeof(T) == sizeof(uint64_t)) ? __builtin_ctzll(x) : __builtin_ctz(x); } // Similar to CTZ except that on zero input it returns bitwidth and supports signed integers. |