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| author | Max Graey <maxgraey@gmail.com> | 2020-06-18 04:13:59 +0300 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2020-06-17 18:13:59 -0700 |
| commit | f6eb790eec107064798b9e54552f1ef5966f6359 (patch) | |
| tree | 25a51d7cb2d0722dc2ab015d10abc59078916477 /src/support/bits.h | |
| parent | 251a68b603080c86cd417db4f02801510376b279 (diff) | |
| download | binaryen-f6eb790eec107064798b9e54552f1ef5966f6359.tar.gz binaryen-f6eb790eec107064798b9e54552f1ef5966f6359.tar.bz2 binaryen-f6eb790eec107064798b9e54552f1ef5966f6359.zip | |
Optimize bit count polyfills (#2914)
Diffstat (limited to 'src/support/bits.h')
| -rw-r--r-- | src/support/bits.h | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/src/support/bits.h b/src/support/bits.h index f2241bea8..bd91fdec6 100644 --- a/src/support/bits.h +++ b/src/support/bits.h @@ -65,17 +65,21 @@ template<typename T> int CountTrailingZeroes(T v) { template<typename T> int CountLeadingZeroes(T v) { return CountLeadingZeroes(typename std::make_unsigned<T>::type(v)); } -template<typename T> bool IsPowerOf2(T v) { return v != 0 && PopCount(v) == 1; } +template<typename T> bool IsPowerOf2(T v) { + return v != 0 && (v & (v - 1)) == 0; +} template<typename T, typename U> inline static T RotateLeft(T val, U count) { - T mask = sizeof(T) * CHAR_BIT - 1; + auto value = typename std::make_unsigned<T>::type(val); + U mask = sizeof(T) * CHAR_BIT - 1; count &= mask; - return (val << count) | (val >> (-count & mask)); + return (value << count) | (value >> (-count & mask)); } template<typename T, typename U> inline static T RotateRight(T val, U count) { - T mask = sizeof(T) * CHAR_BIT - 1; + auto value = typename std::make_unsigned<T>::type(val); + U mask = sizeof(T) * CHAR_BIT - 1; count &= mask; - return (val >> count) | (val << (-count & mask)); + return (value >> count) | (value << (-count & mask)); } extern uint32_t Log2(uint32_t v); |