diff options
Diffstat (limited to 'include/llvm/Support/MathExtras.h')
| -rw-r--r-- | include/llvm/Support/MathExtras.h | 27 |
1 files changed, 16 insertions, 11 deletions
diff --git a/include/llvm/Support/MathExtras.h b/include/llvm/Support/MathExtras.h index f660d48d86..6ba51d6d58 100644 --- a/include/llvm/Support/MathExtras.h +++ b/include/llvm/Support/MathExtras.h @@ -208,22 +208,27 @@ inline unsigned CountTrailingZeros_64(uint64_t Value) { /// CountPopulation_32 - this function counts the number of set bits in a value. /// Ex. CountPopulation(0xF000F000) = 8 /// Returns 0 if the word is zero. -inline unsigned CountPopulation_32(unsigned Value) { - unsigned x, t; - x = Value - ((Value >> 1) & 0x55555555); - t = ((x >> 2) & 0x33333333); - x = (x & 0x33333333) + t; - x = (x + (x >> 4)) & 0x0F0F0F0F; - x = x + (x << 8); - x = x + (x << 16); - return x >> 24; +inline unsigned CountPopulation_32(uint32_t Value) { +#if __GNUC__ >= 4 + return __builtin_popcount(Value); +#else + uint32_t v = v - ((v >> 1) & 0x55555555); + v = (v & 0x33333333) + ((v >> 2) & 0x33333333); + return ((v + (v >> 4) & 0xF0F0F0F) * 0x1010101) >> 24; +#endif } /// CountPopulation_64 - this function counts the number of set bits in a value, /// (64 bit edition.) inline unsigned CountPopulation_64(uint64_t Value) { - return CountPopulation_32(unsigned(Value >> 32)) + - CountPopulation_32(unsigned(Value)); +#if __GNUC__ >= 4 + return __builtin_popcountll(Value); +#else + uint64_t v = Value - ((Value >> 1) & 0x5555555555555555ULL); + v = (v & 0x3333333333333333ULL) + ((v >> 2) & 0x3333333333333333ULL); + v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL; + return (uint64_t)(v * 0x0101010101010101ULL) >> 56; +#endif } /// Log2_32 - This function returns the floor log base 2 of the specified value, |