Thanks, pushed!
Jarno
On Dec 11, 2013, at 9:25 PM, Simon Horman <[email protected]> wrote:
> On Wed, Dec 11, 2013 at 03:41:19PM -0800, Jarno Rajahalme wrote:
>> - Use the GCC predefined macro __POPCNT__ to detect the availability
>> of fast __builtin_popcnt function.
>> - Use portable preprocessor macros to detect 64-bit build.
>> - Only define the 32-bit parts when needed and declare the
>> count_1bits_8 at file scope to silence a warning.
>>
>> This time I have tested all code paths to make sure no warnigns are
>> generated.
>>
>> Signed-off-by: Jarno Rajahalme <[email protected]>
>
> No objections here.
>
> Reviewed-by: Simon Horman <[email protected]>
>
>> ---
>> lib/util.c | 2 +-
>> lib/util.h | 62
>> +++++++++++++++++++++++++++++++++---------------------------
>> 2 files changed, 35 insertions(+), 29 deletions(-)
>>
>> diff --git a/lib/util.c b/lib/util.c
>> index 13d41a7..000504c 100644
>> --- a/lib/util.c
>> +++ b/lib/util.c
>> @@ -901,7 +901,7 @@ raw_clz64(uint64_t n)
>> }
>> #endif
>>
>> -#if !(__GNUC__ >= 4 && defined(__corei7))
>> +#if NEED_COUNT_1BITS_8
>> #define INIT1(X) \
>> ((((X) & (1 << 0)) != 0) + \
>> (((X) & (1 << 1)) != 0) + \
>> diff --git a/lib/util.h b/lib/util.h
>> index 8d810c2..0327ab0 100644
>> --- a/lib/util.h
>> +++ b/lib/util.h
>> @@ -371,49 +371,55 @@ log_2_ceil(uint64_t n)
>> return log_2_floor(n) + !is_pow2(n);
>> }
>>
>> -extern const uint8_t count_1bits_8[256];
>> -
>> -/* Returns the number of 1-bits in 'x', between 0 and 32 inclusive. */
>> +/* unsigned int count_1bits(uint64_t x):
>> + *
>> + * Returns the number of 1-bits in 'x', between 0 and 64 inclusive. */
>> +#if UINTPTR_MAX == UINT64_MAX
>> +static inline unsigned int
>> +count_1bits(uint64_t x)
>> +{
>> +#if __GNUC__ >= 4 && __POPCNT__
>> + return __builtin_popcountll(x);
>> +#else
>> + /* This portable implementation is the fastest one we know of for 64
>> + * bits, and about 3x faster than GCC 4.7 __builtin_popcountll(). */
>> + const uint64_t h55 = UINT64_C(0x5555555555555555);
>> + const uint64_t h33 = UINT64_C(0x3333333333333333);
>> + const uint64_t h0F = UINT64_C(0x0F0F0F0F0F0F0F0F);
>> + const uint64_t h01 = UINT64_C(0x0101010101010101);
>> + x -= (x >> 1) & h55; /* Count of each 2 bits in-place. */
>> + x = (x & h33) + ((x >> 2) & h33); /* Count of each 4 bits in-place. */
>> + x = (x + (x >> 4)) & h0F; /* Count of each 8 bits in-place. */
>> + return (x * h01) >> 56; /* Sum of all bytes. */
>> +#endif
>> +}
>> +#else /* Not 64-bit. */
>> +#if __GNUC__ >= 4 && __POPCNT__
>> static inline unsigned int
>> -count_1bits_32(uint32_t x)
>> +count_1bits_32__(uint32_t x)
>> {
>> -#if __GNUC__ >= 4 && defined(__corei7)
>> - /* __builtin_popcount() is fast only when supported by the CPU. */
>> return __builtin_popcount(x);
>> +}
>> #else
>> +#define NEED_COUNT_1BITS_8 1
>> +extern const uint8_t count_1bits_8[256];
>> +static inline unsigned int
>> +count_1bits_32__(uint32_t x)
>> +{
>> /* This portable implementation is the fastest one we know of for 32
>> bits,
>> * and faster than GCC __builtin_popcount(). */
>> return (count_1bits_8[x & 0xff] +
>> count_1bits_8[(x >> 8) & 0xff] +
>> count_1bits_8[(x >> 16) & 0xff] +
>> count_1bits_8[x >> 24]);
>> -#endif
>> }
>> -
>> -/* Returns the number of 1-bits in 'x', between 0 and 64 inclusive. */
>> +#endif
>> static inline unsigned int
>> count_1bits(uint64_t x)
>> {
>> - if (sizeof(void *) == 8) { /* 64-bit CPU */
>> -#if __GNUC__ >= 4 && defined(__corei7)
>> - /* __builtin_popcountll() is fast only when supported by the CPU. */
>> - return __builtin_popcountll(x);
>> -#else
>> - /* This portable implementation is the fastest one we know of for 64
>> - * bits, and about 3x faster than GCC 4.7 __builtin_popcountll(). */
>> - const uint64_t h55 = UINT64_C(0x5555555555555555);
>> - const uint64_t h33 = UINT64_C(0x3333333333333333);
>> - const uint64_t h0F = UINT64_C(0x0F0F0F0F0F0F0F0F);
>> - const uint64_t h01 = UINT64_C(0x0101010101010101);
>> - x -= (x >> 1) & h55; /* Count of each 2 bits
>> in-place. */
>> - x = (x & h33) + ((x >> 2) & h33); /* Count of each 4 bits
>> in-place. */
>> - x = (x + (x >> 4)) & h0F; /* Count of each 8 bits
>> in-place. */
>> - return (x * h01) >> 56; /* Sum of all bytes. */
>> -#endif
>> - } else { /* 32-bit CPU */
>> - return count_1bits_32(x) + count_1bits_32(x >> 32);
>> - }
>> + return count_1bits_32__(x) + count_1bits_32__(x >> 32);
>> }
>> +#endif
>>
>> /* Returns the rightmost 1-bit in 'x' (e.g. 01011000 => 00001000), or 0 if
>> 'x'
>> * is 0. */
>> --
>> 1.7.10.4
>>
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