Sorry, maybe I made a mistake here. Accoring to lib/librte_eal/common/eal_common_cpuflags.c code, it seemed to me that constructor attribute is not supported by intel compiler. So in that case here I decided to leave the code for autodetection. Am I correct?
18.11.2014 9:21, Yerden Zhumabekov ?????: > Initially, SSE4.2 support is detected via CPUID instruction. > > Added rte_hash_crc_set_alg() function to detect and set CRC32 > implementation if necessary. SSE4.2 is allowed by default. If it's > not available, fall back to sw implementation. > > Depending on compiler attributes support, best available algorithm > may be detected upon application startup. > > Signed-off-by: Yerden Zhumabekov <e_zhumabekov at sts.kz> > --- > lib/librte_hash/rte_hash_crc.h | 64 > ++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 62 insertions(+), 2 deletions(-) > > diff --git a/lib/librte_hash/rte_hash_crc.h b/lib/librte_hash/rte_hash_crc.h > index 15f687a..c1b75e8 100644 > --- a/lib/librte_hash/rte_hash_crc.h > +++ b/lib/librte_hash/rte_hash_crc.h > @@ -45,7 +45,11 @@ extern "C" { > #endif > > #include <stdint.h> > +#ifdef RTE_MACHINE_CPUFLAG_SSE4_2 > #include <nmmintrin.h> > +#endif > +#include <rte_cpuflags.h> > +#include <rte_branch_prediction.h> > > /* Lookup tables for software implementation of CRC32C */ > static uint32_t crc32c_tables[8][256] = {{ > @@ -363,8 +367,44 @@ crc32c_2words(uint64_t data, uint32_t init_val) > return crc; > } > > +enum crc32_alg_t { > + CRC32_SW = 0, > + CRC32_SSE42, > + CRC32_AUTODETECT > +}; > + > +static enum crc32_alg_t crc32_alg = CRC32_AUTODETECT; > + > +/** > + * Allow or disallow use of SSE4.2 instrinsics for CRC32 hash > + * calculation. > + * > + * @param flag > + * unsigned integer flag > + * - (CRC32_SW) Don't use SSE4.2 intrinsics > + * - (CRC32_SSE42) Use SSE4.2 intrinsics if available, set by default > + */ > +static inline void > +rte_hash_crc_set_alg(enum crc32_alg_t alg) > +{ > + int sse42_supp = rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE4_2); > + enum crc32_alg_t alg_supp = sse42_supp ? CRC32_SSE42 : CRC32_SW; > + crc32_alg = (alg == CRC32_SSE42) ? alg_supp : CRC32_SW; > +} > + > +/* Best available algorithm is detected via CPUID instruction */ > +#ifndef __INTEL_COMPILER > +static inline void __attribute__((constructor)) > +rte_hash_crc_try_sse42(void) > +{ > + rte_hash_crc_set_alg(CRC32_SSE42); > +} > +#endif > + > /** > * Use single crc32 instruction to perform a hash on a 4 byte value. > + * Fall back to software crc32 implementation in case SSE4.2 is > + * not supported > * > * @param data > * Data to perform hash on. > @@ -376,11 +416,22 @@ crc32c_2words(uint64_t data, uint32_t init_val) > static inline uint32_t > rte_hash_crc_4byte(uint32_t data, uint32_t init_val) > { > - return _mm_crc32_u32(init_val, data); > +#ifdef __INTEL_COMPILER > + if (unlikely(crc32_alg == CRC32_AUTODETECT)) > + rte_hash_crc_set_alg(CRC32_SSE42); > +#endif > +#ifdef RTE_MACHINE_CPUFLAG_SSE4_2 > + if (likely(crc32_alg == CRC32_SSE42)) > + return _mm_crc32_u32(init_val, data); > +#endif > + > + return crc32c_1word(data, init_val); > } > > /** > * Use single crc32 instruction to perform a hash on a 8 byte value. > + * Fall back to software crc32 implementation in case SSE4.2 is > + * not supported > * > * @param data > * Data to perform hash on. > @@ -392,7 +443,16 @@ rte_hash_crc_4byte(uint32_t data, uint32_t init_val) > static inline uint32_t > rte_hash_crc_8byte(uint64_t data, uint32_t init_val) > { > - return _mm_crc32_u64(init_val, data); > +#ifdef __INTEL_COMPILER > + if (unlikely(crc32_alg == CRC32_AUTODETECT)) > + rte_hash_crc_set_alg(CRC32_SSE42); > +#endif > +#ifdef RTE_MACHINE_CPUFLAG_SSE4_2 > + if (likely(crc32_alg == CRC32_SSE42)) > + return _mm_crc32_u64(init_val, data); > +#endif > + > + return crc32c_2words(data, init_val); > } > > /** -- Sincerely, Yerden Zhumabekov State Technical Service Astana, KZ