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mirror_zfs/module/zcommon/zfs_fletcher_aarch64_neon.c
Romain Dolbeau 7f3194932d Add superscalar fletcher4 
This is the Fletcher4 algorithm implemented in pure C, but using
multiple counters using algorithms identical to those used for
SSE/NEON and AVX2.

This allows for faster execution on core with strong superscalar
capabilities but weak SIMD capabilities.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Romain Dolbeau <romain.dolbeau@atos.net>
Closes #5317
2016-11-04 10:53:03 -07:00

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/*
* Implement fast Fletcher4 with NEON instructions. (aarch64)
*
* Use the 128-bit NEON SIMD instructions and registers to compute
* Fletcher4 in two incremental 64-bit parallel accumulator streams,
* and then combine the streams to form the final four checksum words.
* This implementation is a derivative of the AVX SIMD implementation by
* James Guilford and Jinshan Xiong from Intel (see zfs_fletcher_intel.c).
*
* Copyright (C) 2016 Romain Dolbeau.
*
* Authors:
* Romain Dolbeau <romain.dolbeau@atos.net>
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#if defined(__aarch64__)
#include <linux/simd_aarch64.h>
#include <sys/spa_checksum.h>
#include <zfs_fletcher.h>
#include <strings.h>
static void
fletcher_4_aarch64_neon_init(fletcher_4_ctx_t *ctx)
{
bzero(ctx->aarch64_neon, 4 * sizeof (zfs_fletcher_aarch64_neon_t));
}
static void
fletcher_4_aarch64_neon_fini(fletcher_4_ctx_t *ctx, zio_cksum_t *zcp)
{
uint64_t A, B, C, D;
A = ctx->aarch64_neon[0].v[0] + ctx->aarch64_neon[0].v[1];
B = 2 * ctx->aarch64_neon[1].v[0] + 2 * ctx->aarch64_neon[1].v[1] -
ctx->aarch64_neon[0].v[1];
C = 4 * ctx->aarch64_neon[2].v[0] - ctx->aarch64_neon[1].v[0] +
4 * ctx->aarch64_neon[2].v[1] - 3 * ctx->aarch64_neon[1].v[1];
D = 8 * ctx->aarch64_neon[3].v[0] - 4 * ctx->aarch64_neon[2].v[0] +
8 * ctx->aarch64_neon[3].v[1] - 8 * ctx->aarch64_neon[2].v[1] +
ctx->aarch64_neon[1].v[1];
ZIO_SET_CHECKSUM(zcp, A, B, C, D);
}
#define NEON_INIT_LOOP() \
asm("eor %[ZERO].16b,%[ZERO].16b,%[ZERO].16b\n" \
"ld1 { %[ACC0].4s }, %[CTX0]\n" \
"ld1 { %[ACC1].4s }, %[CTX1]\n" \
"ld1 { %[ACC2].4s }, %[CTX2]\n" \
"ld1 { %[ACC3].4s }, %[CTX3]\n" \
: [ZERO] "=w" (ZERO), \
[ACC0] "=w" (ACC0), [ACC1] "=w" (ACC1), \
[ACC2] "=w" (ACC2), [ACC3] "=w" (ACC3) \
: [CTX0] "Q" (ctx->aarch64_neon[0]), \
[CTX1] "Q" (ctx->aarch64_neon[1]), \
[CTX2] "Q" (ctx->aarch64_neon[2]), \
[CTX3] "Q" (ctx->aarch64_neon[3]))
#define NEON_DO_REVERSE "rev32 %[SRC].16b, %[SRC].16b\n"
#define NEON_DONT_REVERSE ""
#define NEON_MAIN_LOOP(REVERSE) \
asm("ld1 { %[SRC].4s }, %[IP]\n" \
REVERSE \
"zip1 %[TMP1].4s, %[SRC].4s, %[ZERO].4s\n" \
"zip2 %[TMP2].4s, %[SRC].4s, %[ZERO].4s\n" \
"add %[ACC0].2d, %[ACC0].2d, %[TMP1].2d\n" \
"add %[ACC1].2d, %[ACC1].2d, %[ACC0].2d\n" \
"add %[ACC2].2d, %[ACC2].2d, %[ACC1].2d\n" \
"add %[ACC3].2d, %[ACC3].2d, %[ACC2].2d\n" \
"add %[ACC0].2d, %[ACC0].2d, %[TMP2].2d\n" \
"add %[ACC1].2d, %[ACC1].2d, %[ACC0].2d\n" \
"add %[ACC2].2d, %[ACC2].2d, %[ACC1].2d\n" \
"add %[ACC3].2d, %[ACC3].2d, %[ACC2].2d\n" \
: [SRC] "=&w" (SRC), \
[TMP1] "=&w" (TMP1), [TMP2] "=&w" (TMP2), \
[ACC0] "+w" (ACC0), [ACC1] "+w" (ACC1), \
[ACC2] "+w" (ACC2), [ACC3] "+w" (ACC3) \
: [ZERO] "w" (ZERO), [IP] "Q" (*ip))
#define NEON_FINI_LOOP() \
asm("st1 { %[ACC0].4s },%[DST0]\n" \
"st1 { %[ACC1].4s },%[DST1]\n" \
"st1 { %[ACC2].4s },%[DST2]\n" \
"st1 { %[ACC3].4s },%[DST3]\n" \
: [DST0] "=Q" (ctx->aarch64_neon[0]), \
[DST1] "=Q" (ctx->aarch64_neon[1]), \
[DST2] "=Q" (ctx->aarch64_neon[2]), \
[DST3] "=Q" (ctx->aarch64_neon[3]) \
: [ACC0] "w" (ACC0), [ACC1] "w" (ACC1), \
[ACC2] "w" (ACC2), [ACC3] "w" (ACC3))
static void
fletcher_4_aarch64_neon_native(fletcher_4_ctx_t *ctx,
const void *buf, uint64_t size)
{
const uint64_t *ip = buf;
const uint64_t *ipend = (uint64_t *)((uint8_t *)ip + size);
#if defined(_KERNEL)
register unsigned char ZERO asm("v0") __attribute__((vector_size(16)));
register unsigned char ACC0 asm("v1") __attribute__((vector_size(16)));
register unsigned char ACC1 asm("v2") __attribute__((vector_size(16)));
register unsigned char ACC2 asm("v3") __attribute__((vector_size(16)));
register unsigned char ACC3 asm("v4") __attribute__((vector_size(16)));
register unsigned char TMP1 asm("v5") __attribute__((vector_size(16)));
register unsigned char TMP2 asm("v6") __attribute__((vector_size(16)));
register unsigned char SRC asm("v7") __attribute__((vector_size(16)));
#else
unsigned char ZERO __attribute__((vector_size(16)));
unsigned char ACC0 __attribute__((vector_size(16)));
unsigned char ACC1 __attribute__((vector_size(16)));
unsigned char ACC2 __attribute__((vector_size(16)));
unsigned char ACC3 __attribute__((vector_size(16)));
unsigned char TMP1 __attribute__((vector_size(16)));
unsigned char TMP2 __attribute__((vector_size(16)));
unsigned char SRC __attribute__((vector_size(16)));
#endif
kfpu_begin();
NEON_INIT_LOOP();
for (; ip < ipend; ip += 2) {
NEON_MAIN_LOOP(NEON_DONT_REVERSE);
}
NEON_FINI_LOOP();
kfpu_end();
}
static void
fletcher_4_aarch64_neon_byteswap(fletcher_4_ctx_t *ctx,
const void *buf, uint64_t size)
{
const uint64_t *ip = buf;
const uint64_t *ipend = (uint64_t *)((uint8_t *)ip + size);
#if defined(_KERNEL)
register unsigned char ZERO asm("v0") __attribute__((vector_size(16)));
register unsigned char ACC0 asm("v1") __attribute__((vector_size(16)));
register unsigned char ACC1 asm("v2") __attribute__((vector_size(16)));
register unsigned char ACC2 asm("v3") __attribute__((vector_size(16)));
register unsigned char ACC3 asm("v4") __attribute__((vector_size(16)));
register unsigned char TMP1 asm("v5") __attribute__((vector_size(16)));
register unsigned char TMP2 asm("v6") __attribute__((vector_size(16)));
register unsigned char SRC asm("v7") __attribute__((vector_size(16)));
#else
unsigned char ZERO __attribute__((vector_size(16)));
unsigned char ACC0 __attribute__((vector_size(16)));
unsigned char ACC1 __attribute__((vector_size(16)));
unsigned char ACC2 __attribute__((vector_size(16)));
unsigned char ACC3 __attribute__((vector_size(16)));
unsigned char TMP1 __attribute__((vector_size(16)));
unsigned char TMP2 __attribute__((vector_size(16)));
unsigned char SRC __attribute__((vector_size(16)));
#endif
kfpu_begin();
NEON_INIT_LOOP();
for (; ip < ipend; ip += 2) {
NEON_MAIN_LOOP(NEON_DO_REVERSE);
}
NEON_FINI_LOOP();
kfpu_end();
}
static boolean_t fletcher_4_aarch64_neon_valid(void)
{
return (B_TRUE);
}
const fletcher_4_ops_t fletcher_4_aarch64_neon_ops = {
.init_native = fletcher_4_aarch64_neon_init,
.compute_native = fletcher_4_aarch64_neon_native,
.fini_native = fletcher_4_aarch64_neon_fini,
.init_byteswap = fletcher_4_aarch64_neon_init,
.compute_byteswap = fletcher_4_aarch64_neon_byteswap,
.fini_byteswap = fletcher_4_aarch64_neon_fini,
.valid = fletcher_4_aarch64_neon_valid,
.name = "aarch64_neon"
};
#endif /* defined(__aarch64__) */
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