vpx/vpx_dsp/arm/subpel_variance_neon.c
Johann f3c97ed32e subpel variance neon: reduce stack usage
Unlike x86, arm does not impose additional alignment restrictions on
vector loads. For incoming values to the first pass, it uses vld1_u32()
which typically does impose a 4 byte alignment. However, as the first
pass operates on user-supplied values we must prepare for unaligned
values anyway (and have, see mem_neon.h).

But for the local temporary values there is no stride and the load will
use vld1_u8 which does not require 4 byte alignment.

There are 3 temporary structures. In the C, one is uint16_t. The arm
saturates between passes but still passes tests. If this becomes an
issue new functions will be needed.

Change-Id: I3c9d4701bfeb14b77c783d0164608e621bfecfb1
2017-05-24 13:28:13 -07:00

185 lines
8.5 KiB
C

/*
* Copyright (c) 2014 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include <arm_neon.h>
#include "./vpx_dsp_rtcd.h"
#include "./vpx_config.h"
#include "vpx/vpx_integer.h"
#include "vpx_dsp/variance.h"
#include "vpx_dsp/arm/mem_neon.h"
static const uint8_t bilinear_filters[8][2] = {
{ 128, 0 }, { 112, 16 }, { 96, 32 }, { 80, 48 },
{ 64, 64 }, { 48, 80 }, { 32, 96 }, { 16, 112 },
};
// Process a block exactly 4 wide and a multiple of 2 high.
static void var_filter_block2d_bil_w4(const uint8_t *src_ptr,
uint8_t *output_ptr,
unsigned int src_pixels_per_line,
int pixel_step,
unsigned int output_height,
const uint8_t *filter) {
const uint8x8_t f0 = vdup_n_u8(filter[0]);
const uint8x8_t f1 = vdup_n_u8(filter[1]);
unsigned int i;
for (i = 0; i < output_height; i += 2) {
const uint8x8_t src_0 = load_unaligned_u8(src_ptr, src_pixels_per_line);
const uint8x8_t src_1 =
load_unaligned_u8(src_ptr + pixel_step, src_pixels_per_line);
const uint16x8_t a = vmull_u8(src_0, f0);
const uint16x8_t b = vmlal_u8(a, src_1, f1);
const uint8x8_t out = vrshrn_n_u16(b, FILTER_BITS);
vst1_u8(output_ptr, out);
src_ptr += 2 * src_pixels_per_line;
output_ptr += 8;
}
}
// Process a block exactly 8 wide and any height.
static void var_filter_block2d_bil_w8(const uint8_t *src_ptr,
uint8_t *output_ptr,
unsigned int src_pixels_per_line,
int pixel_step,
unsigned int output_height,
const uint8_t *filter) {
const uint8x8_t f0 = vdup_n_u8(filter[0]);
const uint8x8_t f1 = vdup_n_u8(filter[1]);
unsigned int i;
for (i = 0; i < output_height; ++i) {
const uint8x8_t src_0 = vld1_u8(&src_ptr[0]);
const uint8x8_t src_1 = vld1_u8(&src_ptr[pixel_step]);
const uint16x8_t a = vmull_u8(src_0, f0);
const uint16x8_t b = vmlal_u8(a, src_1, f1);
const uint8x8_t out = vrshrn_n_u16(b, FILTER_BITS);
vst1_u8(output_ptr, out);
src_ptr += src_pixels_per_line;
output_ptr += 8;
}
}
// Process a block which is a mutiple of 16 wide and any height.
static void var_filter_block2d_bil_w16(const uint8_t *src_ptr,
uint8_t *output_ptr,
unsigned int src_pixels_per_line,
int pixel_step,
unsigned int output_height,
unsigned int output_width,
const uint8_t *filter) {
const uint8x8_t f0 = vdup_n_u8(filter[0]);
const uint8x8_t f1 = vdup_n_u8(filter[1]);
unsigned int i, j;
for (i = 0; i < output_height; ++i) {
for (j = 0; j < output_width; j += 16) {
const uint8x16_t src_0 = vld1q_u8(&src_ptr[j]);
const uint8x16_t src_1 = vld1q_u8(&src_ptr[j + pixel_step]);
const uint16x8_t a = vmull_u8(vget_low_u8(src_0), f0);
const uint16x8_t b = vmlal_u8(a, vget_low_u8(src_1), f1);
const uint8x8_t out_lo = vrshrn_n_u16(b, FILTER_BITS);
const uint16x8_t c = vmull_u8(vget_high_u8(src_0), f0);
const uint16x8_t d = vmlal_u8(c, vget_high_u8(src_1), f1);
const uint8x8_t out_hi = vrshrn_n_u16(d, FILTER_BITS);
vst1q_u8(output_ptr + j, vcombine_u8(out_lo, out_hi));
}
src_ptr += src_pixels_per_line;
output_ptr += output_width;
}
}
// 4xM filter writes an extra row to fdata because it processes two rows at a
// time.
#define sub_pixel_varianceNxM(n, m) \
uint32_t vpx_sub_pixel_variance##n##x##m##_neon( \
const uint8_t *a, int a_stride, int xoffset, int yoffset, \
const uint8_t *b, int b_stride, uint32_t *sse) { \
uint8_t temp0[n * (m + (n == 4 ? 2 : 1))]; \
uint8_t temp1[n * m]; \
\
if (n == 4) { \
var_filter_block2d_bil_w4(a, temp0, a_stride, 1, (m + 2), \
bilinear_filters[xoffset]); \
var_filter_block2d_bil_w4(temp0, temp1, n, n, m, \
bilinear_filters[yoffset]); \
} else if (n == 8) { \
var_filter_block2d_bil_w8(a, temp0, a_stride, 1, (m + 1), \
bilinear_filters[xoffset]); \
var_filter_block2d_bil_w8(temp0, temp1, n, n, m, \
bilinear_filters[yoffset]); \
} else { \
var_filter_block2d_bil_w16(a, temp0, a_stride, 1, (m + 1), n, \
bilinear_filters[xoffset]); \
var_filter_block2d_bil_w16(temp0, temp1, n, n, m, n, \
bilinear_filters[yoffset]); \
} \
return vpx_variance##n##x##m(temp1, n, b, b_stride, sse); \
}
sub_pixel_varianceNxM(4, 4);
sub_pixel_varianceNxM(4, 8);
sub_pixel_varianceNxM(8, 4);
sub_pixel_varianceNxM(8, 8);
sub_pixel_varianceNxM(8, 16);
sub_pixel_varianceNxM(16, 8);
sub_pixel_varianceNxM(16, 16);
sub_pixel_varianceNxM(16, 32);
sub_pixel_varianceNxM(32, 16);
sub_pixel_varianceNxM(32, 32);
sub_pixel_varianceNxM(32, 64);
sub_pixel_varianceNxM(64, 32);
sub_pixel_varianceNxM(64, 64);
// 4xM filter writes an extra row to fdata because it processes two rows at a
// time.
#define sub_pixel_avg_varianceNxM(n, m) \
uint32_t vpx_sub_pixel_avg_variance##n##x##m##_neon( \
const uint8_t *a, int a_stride, int xoffset, int yoffset, \
const uint8_t *b, int b_stride, uint32_t *sse, \
const uint8_t *second_pred) { \
uint8_t temp0[n * (m + (n == 4 ? 2 : 1))]; \
uint8_t temp1[n * m]; \
\
if (n == 4) { \
var_filter_block2d_bil_w4(a, temp0, a_stride, 1, (m + 2), \
bilinear_filters[xoffset]); \
var_filter_block2d_bil_w4(temp0, temp1, n, n, m, \
bilinear_filters[yoffset]); \
} else if (n == 8) { \
var_filter_block2d_bil_w8(a, temp0, a_stride, 1, (m + 1), \
bilinear_filters[xoffset]); \
var_filter_block2d_bil_w8(temp0, temp1, n, n, m, \
bilinear_filters[yoffset]); \
} else { \
var_filter_block2d_bil_w16(a, temp0, a_stride, 1, (m + 1), n, \
bilinear_filters[xoffset]); \
var_filter_block2d_bil_w16(temp0, temp1, n, n, m, n, \
bilinear_filters[yoffset]); \
} \
\
vpx_comp_avg_pred(temp0, second_pred, n, m, temp1, n); \
\
return vpx_variance##n##x##m(temp0, n, b, b_stride, sse); \
}
sub_pixel_avg_varianceNxM(4, 4);
sub_pixel_avg_varianceNxM(4, 8);
sub_pixel_avg_varianceNxM(8, 4);
sub_pixel_avg_varianceNxM(8, 8);
sub_pixel_avg_varianceNxM(8, 16);
sub_pixel_avg_varianceNxM(16, 8);
sub_pixel_avg_varianceNxM(16, 16);
sub_pixel_avg_varianceNxM(16, 32);
sub_pixel_avg_varianceNxM(32, 16);
sub_pixel_avg_varianceNxM(32, 32);
sub_pixel_avg_varianceNxM(32, 64);
sub_pixel_avg_varianceNxM(64, 32);
sub_pixel_avg_varianceNxM(64, 64);