RE: [dpdk-dev] [PATCH v5 2/2] hash: unify crc32 selection for x86 and Arm

[Ruifeng Wang <Ruifeng.Wang@arm.com>]

> -----Original Message-----
> From: pbhagavatula@marvell.com <pbhagavatula@marvell.com>
> Sent: Friday, November 5, 2021 6:11 PM
> To: Ruifeng Wang <Ruifeng.Wang@arm.com>; david.marchand@redhat.com;
> jerinj@marvell.com; Yipeng Wang <yipeng1.wang@intel.com>; Sameh
> Gobriel <sameh.gobriel@intel.com>; Bruce Richardson
> <bruce.richardson@intel.com>; Vladimir Medvedkin
> <vladimir.medvedkin@intel.com>
> Cc: dev@dpdk.org; Pavan Nikhilesh <pbhagavatula@marvell.com>
> Subject: [dpdk-dev] [PATCH v5 2/2] hash: unify crc32 selection for x86 and
> Arm
> 
> From: Pavan Nikhilesh <pbhagavatula@marvell.com>
> 
> Merge crc32 hash calculation public API implementation for x86 and Arm.
> Select the best available CRC32 algorithm when unsupported algorithm on a
> given CPU architecture is requested by an application.
> 
> Previously, if an application directly includes `rte_crc_arm64.h` without
> including `rte_hash_crc.h` it will fail to compile.
> 
> Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
> ---
>  .../{rte_crc_arm64.h => hash_crc_arm64.h}     |  69 +-------
>  lib/hash/hash_crc_x86.h                       |  89 ++++++++++
>  lib/hash/meson.build                          |   1 -
>  lib/hash/rte_hash_crc.h                       | 154 +++++-------------
>  4 files changed, 143 insertions(+), 170 deletions(-)  rename
> lib/hash/{rte_crc_arm64.h => hash_crc_arm64.h} (65%)
> 
<snip>

> diff --git a/lib/hash/rte_hash_crc.h b/lib/hash/rte_hash_crc.h index
> 1cc8f84fe2..ea5ef302b8 100644
> --- a/lib/hash/rte_hash_crc.h
> +++ b/lib/hash/rte_hash_crc.h
> @@ -16,10 +16,12 @@ extern "C" {
>  #endif
> 
>  #include <stdint.h>
> -#include <rte_config.h>
> -#include <rte_cpuflags.h>
> +
>  #include <rte_branch_prediction.h>
>  #include <rte_common.h>
> +#include <rte_config.h>
> +#include <rte_cpuflags.h>
> +#include <rte_log.h>
> 
>  #include <hash_crc_sw.h>
> 
> @@ -32,137 +34,71 @@ extern "C" {
>  static uint8_t crc32_alg = CRC32_SW;
> 
>  #if defined(RTE_ARCH_ARM64) && defined(__ARM_FEATURE_CRC32) -
> #include "rte_crc_arm64.h"
> -#else
> +#include "hash_crc_arm64.h"
> +#elif defined(RTE_ARCH_X86)
>  #include "hash_crc_x86.h"
> +#endif
> 
>  /**
> - * Allow or disallow use of SSE4.2 instrinsics for CRC32 hash
> + * Allow or disallow use of SSE4.2/ARMv8 intrinsics for CRC32 hash
>   * calculation.
>   *
>   * @param alg
>   *   An OR of following flags:
> - *   - (CRC32_SW) Don't use SSE4.2 intrinsics
> + *   - (CRC32_SW) Don't use SSE4.2/ARMv8 intrinsics (default non-
> [x86/ARMv8])
>   *   - (CRC32_SSE42) Use SSE4.2 intrinsics if available
> - *   - (CRC32_SSE42_x64) Use 64-bit SSE4.2 intrinsic if available (default)
> + *   - (CRC32_SSE42_x64) Use 64-bit SSE4.2 intrinsic if available (default x86)
> + *   - (CRC32_ARM64) Use ARMv8 CRC intrinsic if available (default ARMv8)
>   *
>   */
>  static inline void
>  rte_hash_crc_set_alg(uint8_t alg)
>  {
> -#if defined(RTE_ARCH_X86)
> -	if (alg == CRC32_SSE42_x64 &&
> -			!rte_cpu_get_flag_enabled(RTE_CPUFLAG_EM64T))
> -		alg = CRC32_SSE42;
> -#endif
> -	crc32_alg = alg;
> -}
> -
> -/* Setting the best available algorithm */
> -RTE_INIT(rte_hash_crc_init_alg)
> -{
> -	rte_hash_crc_set_alg(CRC32_SSE42_x64);
> -}
> -
> -/**
> - * Use single crc32 instruction to perform a hash on a byte value.
> - * Fall back to software crc32 implementation in case SSE4.2 is
> - * not supported
> - *
> - * @param data
> - *   Data to perform hash on.
> - * @param init_val
> - *   Value to initialise hash generator.
> - * @return
> - *   32bit calculated hash value.
> - */
> -static inline uint32_t
> -rte_hash_crc_1byte(uint8_t data, uint32_t init_val) -{
> +	switch (alg) {
> +	case CRC32_SSE42_x64:
> +	case CRC32_SSE42:
>  #if defined RTE_ARCH_X86
> -	if (likely(crc32_alg & CRC32_SSE42))
> -		return crc32c_sse42_u8(data, init_val);
> +		if (!rte_cpu_get_flag_enabled(RTE_CPUFLAG_EM64T))
> +			crc32_alg = CRC32_SSE42;
> +		else
> +			crc32_alg = alg;
>  #endif
> -
> -	return crc32c_1byte(data, init_val);
> -}
> -
> -/**
> - * Use single crc32 instruction to perform a hash on a 2 bytes value.
> - * Fall back to software crc32 implementation in case SSE4.2 is
> - * not supported
> - *
> - * @param data
> - *   Data to perform hash on.
> - * @param init_val
> - *   Value to initialise hash generator.
> - * @return
> - *   32bit calculated hash value.
> - */
> -static inline uint32_t
> -rte_hash_crc_2byte(uint16_t data, uint32_t init_val) -{ -#if defined
> RTE_ARCH_X86
> -	if (likely(crc32_alg & CRC32_SSE42))
> -		return crc32c_sse42_u16(data, init_val);
> +#if defined RTE_ARCH_ARM64
> +		RTE_LOG(WARNING, HASH,
> +			"Incorrect CRC32 algorithm requested setting best
> available algorithm on the architecture\n");
> +		rte_hash_crc_set_alg(CRC32_ARM64);
> +#endif
> +		break;
> +	case CRC32_ARM64:
> +#if defined RTE_ARCH_ARM64
> +		if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_CRC32))
> +			crc32_alg = CRC32_ARM64;
>  #endif
> + #if defined RTE_ARCH_X86
> +		RTE_LOG(WARNING, HASH,
> +			"Incorrect CRC32 algorithm requested setting best
> available algorithm on the architecture\n");
> +		rte_hash_crc_set_alg(CRC32_SSE42_x64);
>  #endif
> +		break;

I edited this part for readability. 
The 'break' need to be inside #if, so algorithm can fallback to CRC32_SW  when CRC32 feature is not available on hardware.

> +	case CRC32_SW:
> +	default:
> +		crc32_alg = CRC32_SW;
> +		break;
> +	}
>  }
> 
> -/**
> - * 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.
> - * @param init_val
> - *   Value to initialise hash generator.
> - * @return
> - *   32bit calculated hash value.
> - */
> -static inline uint32_t
> -rte_hash_crc_8byte(uint64_t data, uint32_t init_val)
> +/* Setting the best available algorithm */
> +RTE_INIT(rte_hash_crc_init_alg)
>  {
> -#ifdef RTE_ARCH_X86_64
> -	if (likely(crc32_alg == CRC32_SSE42_x64))
> -		return crc32c_sse42_u64(data, init_val);
> -#endif
> -
> -#if defined RTE_ARCH_X86
> -	if (likely(crc32_alg & CRC32_SSE42))
> -		return crc32c_sse42_u64_mimic(data, init_val);
> +#if defined(RTE_ARCH_X86)
> +	rte_hash_crc_set_alg(CRC32_SSE42_x64);
> +#elif defined(RTE_ARCH_ARM64) && defined(__ARM_FEATURE_CRC32)
> +	rte_hash_crc_set_alg(CRC32_ARM64);
> +#else
> +	rte_hash_crc_set_alg(CRC32_SW);
>  #endif
> -
> -	return crc32c_2words(data, init_val);
>  }
> 
> -#endif
> -
>  /**
>   * Calculate CRC32 hash on user-supplied byte array.
>   *
> --
> 2.17.1