From b94952a480b8882e45062ff464e1b5cb838c68e2 Mon Sep 17 00:00:00 2001
From: Jonathan Wright <[EMAIL REDACTED]>
Date: Thu, 8 Aug 2024 17:17:44 +0100
Subject: [PATCH] Add Arm Neon USMMLA impl. for 6-tap dist_wtd_convolve_2d
By permuting the input samples and the 6-tap filter we can use the
Armv8.6 I8MM USMMLA matrix multiply instructions to accelerate the
horizontal pass of dist_wtd_convolve_2d for 6-tap filters. The 2x8 by
8x2 matrix multiply instruction does twice the work of a USDOT dot
product instruction.
We also use this new USMMLA 6-tap path for 4-tap filters since it
uses exactly the same number of instructions as the previous USDOT
implementation.
Change-Id: Ia129e7ec926a58932a4b97d4f51b0780f5842550
---
av1/common/arm/compound_convolve_neon_i8mm.c | 204 ++++++++++++++-----
1 file changed, 151 insertions(+), 53 deletions(-)
diff --git a/av1/common/arm/compound_convolve_neon_i8mm.c b/av1/common/arm/compound_convolve_neon_i8mm.c
index 65f48958f..0ed5c911a 100644
--- a/av1/common/arm/compound_convolve_neon_i8mm.c
+++ b/av1/common/arm/compound_convolve_neon_i8mm.c
@@ -23,50 +23,51 @@ DECLARE_ALIGNED(16, static const uint8_t, dot_prod_permute_tbl[48]) = {
8, 9, 10, 11, 9, 10, 11, 12, 10, 11, 12, 13, 11, 12, 13, 14
};
-static inline int16x4_t convolve4_4_2d_h(uint8x16_t samples,
- const int8x8_t x_filter,
+DECLARE_ALIGNED(16, static const uint8_t, kMatMulPermuteTbl[32]) = {
+ // clang-format off
+ 0, 1, 2, 3, 4, 5, 6, 7, 2, 3, 4, 5, 6, 7, 8, 9,
+ 4, 5, 6, 7, 8, 9, 10, 11, 6, 7, 8, 9, 10, 11, 12, 13
+ // clang-format on
+};
+
+static inline int16x4_t convolve6_4_2d_h(uint8x16_t samples,
+ const int8x16_t x_filter,
const uint8x16_t permute_tbl,
const int32x4_t horiz_const) {
- // Permute samples ready for dot product.
- // { 0, 1, 2, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 5, 6 }
+ // Permute samples ready for matrix multiply.
+ // { 0, 1, 2, 3, 4, 5, 6, 7, 2, 3, 4, 5, 6, 7, 8, 9 }
uint8x16_t permuted_samples = vqtbl1q_u8(samples, permute_tbl);
- // First 4 output values.
- int32x4_t sum = vusdotq_lane_s32(horiz_const, permuted_samples, x_filter, 0);
+ // These instructions multiply a 2x8 matrix (samples) by an 8x2 matrix
+ // (filter), destructively accumulating into the destination register.
+ int32x4_t sum = vusmmlaq_s32(horiz_const, permuted_samples, x_filter);
// We halved the convolution filter values so -1 from the right shift.
return vshrn_n_s32(sum, ROUND0_BITS - 1);
}
-static inline int16x8_t convolve8_8_2d_h(uint8x16_t samples,
- const int8x8_t x_filter,
- const uint8x16x3_t permute_tbl,
+static inline int16x8_t convolve6_8_2d_h(uint8x16_t samples,
+ const int8x16_t x_filter,
+ const uint8x16x2_t permute_tbl,
const int32x4_t horiz_const) {
- uint8x16_t permuted_samples[3];
- int32x4_t sum[2];
+ // Permute samples ready for matrix multiply.
+ // { 0, 1, 2, 3, 4, 5, 6, 7, 2, 3, 4, 5, 6, 7, 8, 9 }
+ // { 4, 5, 6, 7, 8, 9, 10, 11, 6, 7, 8, 9, 10, 11, 12, 13 }
+ uint8x16_t permuted_samples[2] = { vqtbl1q_u8(samples, permute_tbl.val[0]),
+ vqtbl1q_u8(samples, permute_tbl.val[1]) };
- // Permute samples ready for dot product.
- // { 0, 1, 2, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 5, 6 }
- permuted_samples[0] = vqtbl1q_u8(samples, permute_tbl.val[0]);
- // { 4, 5, 6, 7, 5, 6, 7, 8, 6, 7, 8, 9, 7, 8, 9, 10 }
- permuted_samples[1] = vqtbl1q_u8(samples, permute_tbl.val[1]);
- // { 8, 9, 10, 11, 9, 10, 11, 12, 10, 11, 12, 13, 11, 12, 13, 14 }
- permuted_samples[2] = vqtbl1q_u8(samples, permute_tbl.val[2]);
-
- // First 4 output values.
- sum[0] = vusdotq_lane_s32(horiz_const, permuted_samples[0], x_filter, 0);
- sum[0] = vusdotq_lane_s32(sum[0], permuted_samples[1], x_filter, 1);
- // Second 4 output values.
- sum[1] = vusdotq_lane_s32(horiz_const, permuted_samples[1], x_filter, 0);
- sum[1] = vusdotq_lane_s32(sum[1], permuted_samples[2], x_filter, 1);
+ // These instructions multiply a 2x8 matrix (samples) by an 8x2 matrix
+ // (filter), destructively accumulating into the destination register.
+ int32x4_t sum0123 = vusmmlaq_s32(horiz_const, permuted_samples[0], x_filter);
+ int32x4_t sum4567 = vusmmlaq_s32(horiz_const, permuted_samples[1], x_filter);
// Narrow and re-pack.
// We halved the convolution filter values so -1 from the right shift.
- return vcombine_s16(vshrn_n_s32(sum[0], ROUND0_BITS - 1),
- vshrn_n_s32(sum[1], ROUND0_BITS - 1));
+ return vcombine_s16(vshrn_n_s32(sum0123, ROUND0_BITS - 1),
+ vshrn_n_s32(sum4567, ROUND0_BITS - 1));
}
-static inline void dist_wtd_convolve_2d_horiz_neon_i8mm(
+static inline void dist_wtd_convolve_2d_horiz_6tap_neon_i8mm(
const uint8_t *src, int src_stride, int16_t *im_block, const int im_stride,
const int16_t *x_filter_ptr, const int im_h, int w) {
const int bd = 8;
@@ -76,28 +77,28 @@ static inline void dist_wtd_convolve_2d_horiz_neon_i8mm(
const int32x4_t horiz_const = vdupq_n_s32((1 << (bd + FILTER_BITS - 2)) +
(1 << ((ROUND0_BITS - 1) - 1)));
+ // Filter values are even, so halve to reduce intermediate precision reqs.
+ const int8x8_t x_filter_s8 = vshrn_n_s16(vld1q_s16(x_filter_ptr), 1);
+ // Stagger the filter for use with the matrix multiply instructions.
+ // { f0, f1, f2, f3, f4, f5, 0, 0, 0, f0, f1, f2, f3, f4, f5, 0 }
+ const int8x16_t x_filter =
+ vcombine_s8(vext_s8(x_filter_s8, x_filter_s8, 1), x_filter_s8);
+
const uint8_t *src_ptr = src;
int16_t *dst_ptr = im_block;
int dst_stride = im_stride;
int height = im_h;
if (w == 4) {
- const uint8x16_t permute_tbl = vld1q_u8(dot_prod_permute_tbl);
- // 4-tap filters are used for blocks having width <= 4.
- // Filter values are even, so halve to reduce intermediate precision reqs.
- const int8x8_t x_filter =
- vshrn_n_s16(vcombine_s16(vld1_s16(x_filter_ptr + 2), vdup_n_s16(0)), 1);
-
- src_ptr += 2;
-
+ const uint8x16_t permute_tbl = vld1q_u8(kMatMulPermuteTbl);
do {
uint8x16_t s0, s1, s2, s3;
load_u8_16x4(src_ptr, src_stride, &s0, &s1, &s2, &s3);
- int16x4_t d0 = convolve4_4_2d_h(s0, x_filter, permute_tbl, horiz_const);
- int16x4_t d1 = convolve4_4_2d_h(s1, x_filter, permute_tbl, horiz_const);
- int16x4_t d2 = convolve4_4_2d_h(s2, x_filter, permute_tbl, horiz_const);
- int16x4_t d3 = convolve4_4_2d_h(s3, x_filter, permute_tbl, horiz_const);
+ int16x4_t d0 = convolve6_4_2d_h(s0, x_filter, permute_tbl, horiz_const);
+ int16x4_t d1 = convolve6_4_2d_h(s1, x_filter, permute_tbl, horiz_const);
+ int16x4_t d2 = convolve6_4_2d_h(s2, x_filter, permute_tbl, horiz_const);
+ int16x4_t d3 = convolve6_4_2d_h(s3, x_filter, permute_tbl, horiz_const);
store_s16_4x4(dst_ptr, dst_stride, d0, d1, d2, d3);
@@ -109,7 +110,7 @@ static inline void dist_wtd_convolve_2d_horiz_neon_i8mm(
do {
uint8x16_t s0 = vld1q_u8(src_ptr);
- int16x4_t d0 = convolve4_4_2d_h(s0, x_filter, permute_tbl, horiz_const);
+ int16x4_t d0 = convolve6_4_2d_h(s0, x_filter, permute_tbl, horiz_const);
vst1_s16(dst_ptr, d0);
@@ -117,10 +118,7 @@ static inline void dist_wtd_convolve_2d_horiz_neon_i8mm(
dst_ptr += dst_stride;
} while (--height != 0);
} else {
- const uint8x16x3_t permute_tbl = vld1q_u8_x3(dot_prod_permute_tbl);
- // Filter values are even, so halve to reduce intermediate precision reqs.
- const int8x8_t x_filter = vshrn_n_s16(vld1q_s16(x_filter_ptr), 1);
-
+ const uint8x16x2_t permute_tbl = vld1q_u8_x2(kMatMulPermuteTbl);
do {
const uint8_t *s = src_ptr;
int16_t *d = dst_ptr;
@@ -130,10 +128,10 @@ static inline void dist_wtd_convolve_2d_horiz_neon_i8mm(
uint8x16_t s0, s1, s2, s3;
load_u8_16x4(s, src_stride, &s0, &s1, &s2, &s3);
- int16x8_t d0 = convolve8_8_2d_h(s0, x_filter, permute_tbl, horiz_const);
- int16x8_t d1 = convolve8_8_2d_h(s1, x_filter, permute_tbl, horiz_const);
- int16x8_t d2 = convolve8_8_2d_h(s2, x_filter, permute_tbl, horiz_const);
- int16x8_t d3 = convolve8_8_2d_h(s3, x_filter, permute_tbl, horiz_const);
+ int16x8_t d0 = convolve6_8_2d_h(s0, x_filter, permute_tbl, horiz_const);
+ int16x8_t d1 = convolve6_8_2d_h(s1, x_filter, permute_tbl, horiz_const);
+ int16x8_t d2 = convolve6_8_2d_h(s2, x_filter, permute_tbl, horiz_const);
+ int16x8_t d3 = convolve6_8_2d_h(s3, x_filter, permute_tbl, horiz_const);
store_s16_8x4(d, dst_stride, d0, d1, d2, d3);
@@ -154,7 +152,7 @@ static inline void dist_wtd_convolve_2d_horiz_neon_i8mm(
do {
uint8x16_t s0 = vld1q_u8(s);
- int16x8_t d0 = convolve8_8_2d_h(s0, x_filter, permute_tbl, horiz_const);
+ int16x8_t d0 = convolve6_8_2d_h(s0, x_filter, permute_tbl, horiz_const);
vst1q_s16(d, d0);
@@ -168,6 +166,99 @@ static inline void dist_wtd_convolve_2d_horiz_neon_i8mm(
}
}
+static inline int16x8_t convolve8_8_2d_h(uint8x16_t samples,
+ const int8x8_t x_filter,
+ const uint8x16x3_t permute_tbl,
+ const int32x4_t horiz_const) {
+ uint8x16_t permuted_samples[3];
+ int32x4_t sum[2];
+
+ // Permute samples ready for dot product.
+ // { 0, 1, 2, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 5, 6 }
+ permuted_samples[0] = vqtbl1q_u8(samples, permute_tbl.val[0]);
+ // { 4, 5, 6, 7, 5, 6, 7, 8, 6, 7, 8, 9, 7, 8, 9, 10 }
+ permuted_samples[1] = vqtbl1q_u8(samples, permute_tbl.val[1]);
+ // { 8, 9, 10, 11, 9, 10, 11, 12, 10, 11, 12, 13, 11, 12, 13, 14 }
+ permuted_samples[2] = vqtbl1q_u8(samples, permute_tbl.val[2]);
+
+ // First 4 output values.
+ sum[0] = vusdotq_lane_s32(horiz_const, permuted_samples[0], x_filter, 0);
+ sum[0] = vusdotq_lane_s32(sum[0], permuted_samples[1], x_filter, 1);
+ // Second 4 output values.
+ sum[1] = vusdotq_lane_s32(horiz_const, permuted_samples[1], x_filter, 0);
+ sum[1] = vusdotq_lane_s32(sum[1], permuted_samples[2], x_filter, 1);
+
+ // Narrow and re-pack.
+ // We halved the convolution filter values so -1 from the right shift.
+ return vcombine_s16(vshrn_n_s32(sum[0], ROUND0_BITS - 1),
+ vshrn_n_s32(sum[1], ROUND0_BITS - 1));
+}
+
+static inline void dist_wtd_convolve_2d_horiz_8tap_neon_i8mm(
+ const uint8_t *src, int src_stride, int16_t *im_block, const int im_stride,
+ const int16_t *x_filter_ptr, const int im_h, int w) {
+ const int bd = 8;
+ // A shim of 1 << ((ROUND0_BITS - 1) - 1) enables us to use non-rounding
+ // shifts - which are generally faster than rounding shifts on modern CPUs.
+ // (The extra -1 is needed because we halved the filter values.)
+ const int32x4_t horiz_const = vdupq_n_s32((1 << (bd + FILTER_BITS - 2)) +
+ (1 << ((ROUND0_BITS - 1) - 1)));
+
+ const uint8x16x3_t permute_tbl = vld1q_u8_x3(dot_prod_permute_tbl);
+ // Filter values are even, so halve to reduce intermediate precision reqs.
+ const int8x8_t x_filter = vshrn_n_s16(vld1q_s16(x_filter_ptr), 1);
+
+ const uint8_t *src_ptr = src;
+ int16_t *dst_ptr = im_block;
+ int dst_stride = im_stride;
+ int height = im_h;
+
+ do {
+ const uint8_t *s = src_ptr;
+ int16_t *d = dst_ptr;
+ int width = w;
+
+ do {
+ uint8x16_t s0, s1, s2, s3;
+ load_u8_16x4(s, src_stride, &s0, &s1, &s2, &s3);
+
+ int16x8_t d0 = convolve8_8_2d_h(s0, x_filter, permute_tbl, horiz_const);
+ int16x8_t d1 = convolve8_8_2d_h(s1, x_filter, permute_tbl, horiz_const);
+ int16x8_t d2 = convolve8_8_2d_h(s2, x_filter, permute_tbl, horiz_const);
+ int16x8_t d3 = convolve8_8_2d_h(s3, x_filter, permute_tbl, horiz_const);
+
+ store_s16_8x4(d, dst_stride, d0, d1, d2, d3);
+
+ s += 8;
+ d += 8;
+ width -= 8;
+ } while (width > 0);
+ src_ptr += 4 * src_stride;
+ dst_ptr += 4 * dst_stride;
+ height -= 4;
+ } while (height > 4);
+
+ do {
+ const uint8_t *s = src_ptr;
+ int16_t *d = dst_ptr;
+ int width = w;
+
+ do {
+ uint8x16_t s0 = vld1q_u8(s);
+
+ int16x8_t d0 = convolve8_8_2d_h(s0, x_filter, permute_tbl, horiz_const);
+
+ vst1q_s16(d, d0);
+
+ s += 8;
+ d += 8;
+ width -= 8;
+ } while (width > 0);
+ src_ptr += src_stride;
+ dst_ptr += dst_stride;
+ } while (--height != 0);
+}
+
void av1_dist_wtd_convolve_2d_neon_i8mm(
const uint8_t *src, int src_stride, uint8_t *dst8, int dst8_stride, int w,
int h, const InterpFilterParams *filter_params_x,
@@ -179,13 +270,15 @@ void av1_dist_wtd_convolve_2d_neon_i8mm(
DECLARE_ALIGNED(16, int16_t,
im_block[(MAX_SB_SIZE + SUBPEL_TAPS - 1) * MAX_SB_SIZE]);
+ const int x_filter_taps = get_filter_tap(filter_params_x, subpel_x_qn);
+ const int clamped_x_taps = x_filter_taps < 6 ? 6 : x_filter_taps;
const int y_filter_taps = get_filter_tap(filter_params_y, subpel_y_qn);
const int clamped_y_taps = y_filter_taps < 6 ? 6 : y_filter_taps;
const int im_h = h + clamped_y_taps - 1;
const int im_stride = MAX_SB_SIZE;
const int vert_offset = clamped_y_taps / 2 - 1;
- const int horiz_offset = filter_params_x->taps / 2 - 1;
+ const int horiz_offset = clamped_x_taps / 2 - 1;
const uint8_t *src_ptr = src - vert_offset * src_stride - horiz_offset;
const int16_t *x_filter_ptr = av1_get_interp_filter_subpel_kernel(
filter_params_x, subpel_x_qn & SUBPEL_MASK);
@@ -194,8 +287,13 @@ void av1_dist_wtd_convolve_2d_neon_i8mm(
const int16x8_t y_filter = vld1q_s16(y_filter_ptr);
- dist_wtd_convolve_2d_horiz_neon_i8mm(src_ptr, src_stride, im_block, im_stride,
- x_filter_ptr, im_h, w);
+ if (clamped_x_taps == 6) {
+ dist_wtd_convolve_2d_horiz_6tap_neon_i8mm(src_ptr, src_stride, im_block,
+ im_stride, x_filter_ptr, im_h, w);
+ } else {
+ dist_wtd_convolve_2d_horiz_8tap_neon_i8mm(src_ptr, src_stride, im_block,
+ im_stride, x_filter_ptr, im_h, w);
+ }
if (clamped_y_taps == 6) {
if (conv_params->do_average) {