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/*-
* Copyright (c) 2014-2016 MongoDB, Inc.
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#ifdef HAVE_X86INTRIN_H
#if !defined(_MSC_VER)
#include <x86intrin.h>
#endif
/* 16B alignment */
#define WT_ALIGNED_16(p) (((uintptr_t)(p) & 0x0f) == 0)
#define WT_VECTOR_SIZE 16 /* chunk size */
#endif
/*
* __wt_lex_compare --
* Lexicographic comparison routine.
*
* Returns:
* < 0 if user_item is lexicographically < tree_item
* = 0 if user_item is lexicographically = tree_item
* > 0 if user_item is lexicographically > tree_item
*
* We use the names "user" and "tree" so it's clear in the btree code which
* the application is looking at when we call its comparison function.
*/
static inline int
__wt_lex_compare(const WT_ITEM *user_item, const WT_ITEM *tree_item)
{
size_t len, usz, tsz;
const uint8_t *userp, *treep;
usz = user_item->size;
tsz = tree_item->size;
len = WT_MIN(usz, tsz);
userp = user_item->data;
treep = tree_item->data;
#ifdef HAVE_X86INTRIN_H
/* Use vector instructions if we'll execute at least 2 of them. */
if (len >= WT_VECTOR_SIZE * 2) {
size_t remain;
__m128i res_eq, u, t;
remain = len % WT_VECTOR_SIZE;
len -= remain;
if (WT_ALIGNED_16(userp) && WT_ALIGNED_16(treep))
for (; len > 0;
len -= WT_VECTOR_SIZE,
userp += WT_VECTOR_SIZE, treep += WT_VECTOR_SIZE) {
u = _mm_load_si128((const __m128i *)userp);
t = _mm_load_si128((const __m128i *)treep);
res_eq = _mm_cmpeq_epi8(u, t);
if (_mm_movemask_epi8(res_eq) != 65535)
break;
}
else
for (; len > 0;
len -= WT_VECTOR_SIZE,
userp += WT_VECTOR_SIZE, treep += WT_VECTOR_SIZE) {
u = _mm_loadu_si128((const __m128i *)userp);
t = _mm_loadu_si128((const __m128i *)treep);
res_eq = _mm_cmpeq_epi8(u, t);
if (_mm_movemask_epi8(res_eq) != 65535)
break;
}
len += remain;
}
#endif
/*
* Use the non-vectorized version for the remaining bytes and for the
* small key sizes.
*/
for (; len > 0; --len, ++userp, ++treep)
if (*userp != *treep)
return (*userp < *treep ? -1 : 1);
/* Contents are equal up to the smallest length. */
return ((usz == tsz) ? 0 : (usz < tsz) ? -1 : 1);
}
/*
* __wt_compare --
* The same as __wt_lex_compare, but using the application's collator
* function when configured.
*/
static inline int
__wt_compare(WT_SESSION_IMPL *session, WT_COLLATOR *collator,
const WT_ITEM *user_item, const WT_ITEM *tree_item, int *cmpp)
{
if (collator == NULL) {
*cmpp = __wt_lex_compare(user_item, tree_item);
return (0);
}
return (collator->compare(
collator, &session->iface, user_item, tree_item, cmpp));
}
/*
* __wt_lex_compare_skip --
* Lexicographic comparison routine, skipping leading bytes.
*
* Returns:
* < 0 if user_item is lexicographically < tree_item
* = 0 if user_item is lexicographically = tree_item
* > 0 if user_item is lexicographically > tree_item
*
* We use the names "user" and "tree" so it's clear in the btree code which
* the application is looking at when we call its comparison function.
*/
static inline int
__wt_lex_compare_skip(
const WT_ITEM *user_item, const WT_ITEM *tree_item, size_t *matchp)
{
size_t len, usz, tsz;
const uint8_t *userp, *treep;
usz = user_item->size;
tsz = tree_item->size;
len = WT_MIN(usz, tsz) - *matchp;
userp = (const uint8_t *)user_item->data + *matchp;
treep = (const uint8_t *)tree_item->data + *matchp;
#ifdef HAVE_X86INTRIN_H
/* Use vector instructions if we'll execute at least 2 of them. */
if (len >= WT_VECTOR_SIZE * 2) {
size_t remain;
__m128i res_eq, u, t;
remain = len % WT_VECTOR_SIZE;
len -= remain;
if (WT_ALIGNED_16(userp) && WT_ALIGNED_16(treep))
for (; len > 0;
len -= WT_VECTOR_SIZE,
userp += WT_VECTOR_SIZE, treep += WT_VECTOR_SIZE,
*matchp += WT_VECTOR_SIZE) {
u = _mm_load_si128((const __m128i *)userp);
t = _mm_load_si128((const __m128i *)treep);
res_eq = _mm_cmpeq_epi8(u, t);
if (_mm_movemask_epi8(res_eq) != 65535)
break;
}
else
for (; len > 0;
len -= WT_VECTOR_SIZE,
userp += WT_VECTOR_SIZE, treep += WT_VECTOR_SIZE,
*matchp += WT_VECTOR_SIZE) {
u = _mm_loadu_si128((const __m128i *)userp);
t = _mm_loadu_si128((const __m128i *)treep);
res_eq = _mm_cmpeq_epi8(u, t);
if (_mm_movemask_epi8(res_eq) != 65535)
break;
}
len += remain;
}
#endif
/*
* Use the non-vectorized version for the remaining bytes and for the
* small key sizes.
*/
for (; len > 0; --len, ++userp, ++treep, ++*matchp)
if (*userp != *treep)
return (*userp < *treep ? -1 : 1);
/* Contents are equal up to the smallest length. */
return ((usz == tsz) ? 0 : (usz < tsz) ? -1 : 1);
}
/*
* __wt_compare_skip --
* The same as __wt_lex_compare_skip, but using the application's collator
* function when configured.
*/
static inline int
__wt_compare_skip(WT_SESSION_IMPL *session, WT_COLLATOR *collator,
const WT_ITEM *user_item, const WT_ITEM *tree_item, int *cmpp,
size_t *matchp)
{
if (collator == NULL) {
*cmpp = __wt_lex_compare_skip(user_item, tree_item, matchp);
return (0);
}
return (collator->compare(
collator, &session->iface, user_item, tree_item, cmpp));
}
/*
* __wt_lex_compare_short --
* Lexicographic comparison routine for short keys.
*
* Returns:
* < 0 if user_item is lexicographically < tree_item
* = 0 if user_item is lexicographically = tree_item
* > 0 if user_item is lexicographically > tree_item
*
* We use the names "user" and "tree" so it's clear in the btree code which
* the application is looking at when we call its comparison function.
*/
static inline int
__wt_lex_compare_short(const WT_ITEM *user_item, const WT_ITEM *tree_item)
{
size_t len, usz, tsz;
const uint8_t *userp, *treep;
usz = user_item->size;
tsz = tree_item->size;
len = WT_MIN(usz, tsz);
userp = user_item->data;
treep = tree_item->data;
/*
* The maximum packed uint64_t is 9B, catch row-store objects using
* packed record numbers as keys.
*/
#define WT_COMPARE_SHORT_MAXLEN 9
#undef WT_COMPARE_SHORT
#define WT_COMPARE_SHORT(n) \
case n: \
if (*userp != *treep) \
break; \
++userp, ++treep
switch (len) {
WT_COMPARE_SHORT(9);
WT_COMPARE_SHORT(8);
WT_COMPARE_SHORT(7);
WT_COMPARE_SHORT(6);
WT_COMPARE_SHORT(5);
WT_COMPARE_SHORT(4);
WT_COMPARE_SHORT(3);
WT_COMPARE_SHORT(2);
case 1:
if (*userp != *treep)
break;
/* Contents are equal up to the smallest length. */
return ((usz == tsz) ? 0 : (usz < tsz) ? -1 : 1);
}
return (*userp < *treep ? -1 : 1);
}
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