pg_lfind.h File Reference

#include "port/simd.h"

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Functions
static bool	pg_lfind8 (uint8 key, uint8 *base, uint32 nelem)
static bool	pg_lfind8_le (uint8 key, uint8 *base, uint32 nelem)
static bool	pg_lfind32_one_by_one_helper (uint32 key, const uint32 *base, uint32 nelem)
static bool	pg_lfind32 (uint32 key, const uint32 *base, uint32 nelem)

Function Documentation

pg_lfind32()

static bool pg_lfind32 ( uint32  key, const uint32 *  base, uint32  nelem  )

inlinestatic

Definition at line 153 of file pg_lfind.h.

{
#ifndef USE_NO_SIMD
    uint32      i = 0;
 
    /*
     * For better instruction-level parallelism, each loop iteration operates
     * on a block of four registers.
     */
    const Vector32 keys = vector32_broadcast(key);  /* load copies of key */
    const uint32 nelem_per_vector = sizeof(Vector32) / sizeof(uint32);
    const uint32 nelem_per_iteration = 4 * nelem_per_vector;
 
    /* round down to multiple of elements per iteration */
    const uint32 tail_idx = nelem & ~(nelem_per_iteration - 1);
 
#if defined(USE_ASSERT_CHECKING)
    bool        assert_result = pg_lfind32_one_by_one_helper(key, base, nelem);
#endif
 
    /*
     * If there aren't enough elements for the SIMD code, use the standard
     * one-by-one linear search code.
     */
    if (nelem < nelem_per_iteration)
        return pg_lfind32_one_by_one_helper(key, base, nelem);
 
    /*
     * Process as many elements as possible with a block of 4 registers.
     */
    do
    {
        if (pg_lfind32_simd_helper(keys, &base[i]))
        {
            Assert(assert_result == true);
            return true;
        }
 
        i += nelem_per_iteration;
 
    } while (i < tail_idx);
 
    /*
     * Process the last 'nelem_per_iteration' elements in the array with a
     * 4-register block.  This will cause us to check a subset of the elements
     * more than once, but that won't affect correctness, and testing has
     * demonstrated that this helps more cases than it harms.
     */
    Assert(assert_result == pg_lfind32_simd_helper(keys, &base[nelem - nelem_per_iteration]));
    return pg_lfind32_simd_helper(keys, &base[nelem - nelem_per_iteration]);
#else
    /* Process the elements one at a time. */
    return pg_lfind32_one_by_one_helper(key, base, nelem);
#endif
}

References Assert, i, sort-test::key, and pg_lfind32_one_by_one_helper().

Referenced by test_lfind32(), TransactionIdIsInProgress(), XidInMVCCSnapshot(), and XidIsConcurrent().

pg_lfind32_one_by_one_helper()

static bool pg_lfind32_one_by_one_helper ( uint32  key, const uint32 *  base, uint32  nelem  )

inlinestatic

Definition at line 90 of file pg_lfind.h.

{
    for (uint32 i = 0; i < nelem; i++)
    {
        if (key == base[i])
            return true;
    }
 
    return false;
}

References i, and sort-test::key.

Referenced by pg_lfind32().

pg_lfind8()

static bool pg_lfind8 ( uint8  key, uint8 *  base, uint32  nelem  )

inlinestatic

Definition at line 26 of file pg_lfind.h.

{
    uint32      i;
 
    /* round down to multiple of vector length */
    uint32      tail_idx = nelem & ~(sizeof(Vector8) - 1);
    Vector8     chunk;
 
    for (i = 0; i < tail_idx; i += sizeof(Vector8))
    {
        vector8_load(&chunk, &base[i]);
        if (vector8_has(chunk, key))
            return true;
    }
 
    /* Process the remaining elements one at a time. */
    for (; i < nelem; i++)
    {
        if (key == base[i])
            return true;
    }
 
    return false;
}

References chunk, i, sort-test::key, vector8_has(), and vector8_load().

Referenced by json_lex_string(), and test_lfind8_internal().

pg_lfind8_le()

static bool pg_lfind8_le ( uint8  key, uint8 *  base, uint32  nelem  )

inlinestatic

Definition at line 58 of file pg_lfind.h.

{
    uint32      i;
 
    /* round down to multiple of vector length */
    uint32      tail_idx = nelem & ~(sizeof(Vector8) - 1);
    Vector8     chunk;
 
    for (i = 0; i < tail_idx; i += sizeof(Vector8))
    {
        vector8_load(&chunk, &base[i]);
        if (vector8_has_le(chunk, key))
            return true;
    }
 
    /* Process the remaining elements one at a time. */
    for (; i < nelem; i++)
    {
        if (base[i] <= key)
            return true;
    }
 
    return false;
}

References chunk, i, sort-test::key, vector8_has_le(), and vector8_load().

Referenced by json_lex_string(), and test_lfind8_le_internal().