rte_lru_x86.h

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2010-2014 Intel Corporation
 */

#ifndef __INCLUDE_RTE_LRU_X86_H__
#define __INCLUDE_RTE_LRU_X86_H__

#ifdef __cplusplus
extern "C" {
#endif

#include <stdint.h>

#include <rte_config.h>

#ifndef RTE_TABLE_HASH_LRU_STRATEGY
#define RTE_TABLE_HASH_LRU_STRATEGY                        2
#endif

#if RTE_TABLE_HASH_LRU_STRATEGY == 2

#if RTE_CC_IS_GNU && (GCC_VERSION > 40306)
#include <x86intrin.h>
#else
#include <emmintrin.h>
#include <smmintrin.h>
#include <xmmintrin.h>
#endif

#define lru_init(bucket)                        \
    { bucket->lru_list = 0x0000000100020003LLU; }

#define lru_pos(bucket) (bucket->lru_list & 0xFFFFLLU)

#define lru_update(bucket, mru_val)                 \
do {                                    \
    /* set up the masks for all possible shuffles, depends on pos */\
    static uint64_t masks[10] = {                   \
        /* Shuffle order; Make Zero (see _mm_shuffle_epi8 manual) */\
        0x0100070605040302, 0x8080808080808080,         \
        0x0302070605040100, 0x8080808080808080,         \
        0x0504070603020100, 0x8080808080808080,         \
        0x0706050403020100, 0x8080808080808080,         \
        0x0706050403020100, 0x8080808080808080};        \
    /* load up one register with repeats of mru-val  */     \
    uint64_t mru2 = mru_val;                    \
    uint64_t mru3 = mru2 | (mru2 << 16);                \
    uint64_t lru = bucket->lru_list;                \
    /* XOR to cause the word we're looking for to go to zero */ \
    uint64_t mru = lru ^ ((mru3 << 32) | mru3);         \
    __m128i c = _mm_cvtsi64_si128(mru);             \
    __m128i b = _mm_cvtsi64_si128(lru);             \
    /* Find the minimum value (first zero word, if it's in there) */\
    __m128i d = _mm_minpos_epu16(c);                \
    /* Second word is the index to found word (first word is the value) */\
    unsigned int pos = _mm_extract_epi16(d, 1);         \
    /* move the recently used location to top of list */        \
    __m128i k = _mm_shuffle_epi8(b, *((__m128i *) &masks[2 * pos]));\
    /* Finally, update the original list with the reordered data */ \
    bucket->lru_list = _mm_extract_epi64(k, 0);         \
    /* Phwew! */                            \
} while (0)

#elif RTE_TABLE_HASH_LRU_STRATEGY == 3

#if RTE_CC_IS_GNU && (GCC_VERSION > 40306)
#include <x86intrin.h>
#else
#include <emmintrin.h>
#include <smmintrin.h>
#include <xmmintrin.h>
#endif

#define lru_init(bucket)                        \
    { bucket->lru_list = ~0LLU; }

static inline int
f_lru_pos(uint64_t lru_list)
{
    __m128i lst = _mm_set_epi64x((uint64_t)-1, lru_list);
    __m128i min = _mm_minpos_epu16(lst);
    return _mm_extract_epi16(min, 1);
}
#define lru_pos(bucket) f_lru_pos(bucket->lru_list)

#define lru_update(bucket, mru_val)                 \
do {                                    \
    const uint64_t orvals[] = {0xFFFFLLU, 0xFFFFLLU << 16,      \
        0xFFFFLLU << 32, 0xFFFFLLU << 48, 0LLU};        \
    const uint64_t decs[] = {0x1000100010001LLU, 0};        \
    __m128i lru = _mm_cvtsi64_si128(bucket->lru_list);      \
    __m128i vdec = _mm_cvtsi64_si128(decs[mru_val>>2]);     \
    lru = _mm_subs_epu16(lru, vdec);                \
    bucket->lru_list = _mm_extract_epi64(lru, 0) | orvals[mru_val]; \
} while (0)

#endif

#ifdef __cplusplus
}
#endif

#endif