aom: Add Neon I8MM implementation for av1_convolve_2d_scale

From 1d0ab49189c19a756015503b529919f145f75f7f Mon Sep 17 00:00:00 2001
From: Gerda Zsejke More <[EMAIL REDACTED]>
Date: Sat, 25 May 2024 17:04:32 +0200
Subject: [PATCH] Add Neon I8MM implementation for av1_convolve_2d_scale

Add an Armv8.6 I8MM implementation for the horizontal filtering part
of av1_convolve_2d_scale.

Add the corresponding tests as well.

Change-Id: Id27aad4e4ce24266cfc75ac8073c38be3fc75eb9
---
 av1/av1.cmake                                 |   1 +
 av1/common/arm/av1_convolve_scale_neon_i8mm.c | 220 ++++++++++++++++++
 av1/common/av1_rtcd_defs.pl                   |   2 +-
 test/av1_convolve_scale_test.cc               |   7 +
 4 files changed, 229 insertions(+), 1 deletion(-)
 create mode 100644 av1/common/arm/av1_convolve_scale_neon_i8mm.c

diff --git a/av1/av1.cmake b/av1/av1.cmake
index f67778a20..99ce3fb68 100644
--- a/av1/av1.cmake
+++ b/av1/av1.cmake
@@ -409,6 +409,7 @@ list(APPEND AOM_AV1_COMMON_INTRIN_NEON_DOTPROD
             "${AOM_ROOT}/av1/common/arm/convolve_neon_dotprod.c")
 
 list(APPEND AOM_AV1_COMMON_INTRIN_NEON_I8MM
+            "${AOM_ROOT}/av1/common/arm/av1_convolve_scale_neon_i8mm.c"
             "${AOM_ROOT}/av1/common/arm/compound_convolve_neon_i8mm.c"
             "${AOM_ROOT}/av1/common/arm/convolve_neon_i8mm.c"
             "${AOM_ROOT}/av1/common/arm/warp_plane_neon_i8mm.c")
diff --git a/av1/common/arm/av1_convolve_scale_neon_i8mm.c b/av1/common/arm/av1_convolve_scale_neon_i8mm.c
new file mode 100644
index 000000000..d1d0ae0c9
--- /dev/null
+++ b/av1/common/arm/av1_convolve_scale_neon_i8mm.c
@@ -0,0 +1,220 @@
+/*
+ * Copyright (c) 2024, Alliance for Open Media. All rights reserved
+ *
+ * This source code is subject to the terms of the BSD 2 Clause License and
+ * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
+ * was not distributed with this source code in the LICENSE file, you can
+ * obtain it at www.aomedia.org/license/software. If the Alliance for Open
+ * Media Patent License 1.0 was not distributed with this source code in the
+ * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
+ */
+
+#include <assert.h>
+#include <arm_neon.h>
+
+#include "config/aom_config.h"
+#include "config/av1_rtcd.h"
+
+#include "aom_dsp/arm/mem_neon.h"
+#include "aom_dsp/arm/transpose_neon.h"
+#include "av1/common/arm/convolve_scale_neon.h"
+
+static INLINE int16x4_t convolve8_4_h(const uint8x8_t s0, const uint8x8_t s1,
+                                      const uint8x8_t s2, const uint8x8_t s3,
+                                      const int8x8_t filter,
+                                      const int32x4_t horiz_const) {
+  const int8x16_t filters = vcombine_s8(filter, filter);
+
+  uint8x16_t s01 = vcombine_u8(s0, s1);
+  uint8x16_t s23 = vcombine_u8(s2, s3);
+
+  int32x4_t sum01 = vusdotq_s32(horiz_const, s01, filters);
+  int32x4_t sum23 = vusdotq_s32(horiz_const, s23, filters);
+
+  int32x4_t sum = vpaddq_s32(sum01, sum23);
+
+  // We halved the filter values so -1 from right shift.
+  return vshrn_n_s32(sum, ROUND0_BITS - 1);
+}
+
+static INLINE int16x8_t convolve8_8_h(const uint8x8_t s0, const uint8x8_t s1,
+                                      const uint8x8_t s2, const uint8x8_t s3,
+                                      const uint8x8_t s4, const uint8x8_t s5,
+                                      const uint8x8_t s6, const uint8x8_t s7,
+                                      const int8x8_t filter,
+                                      const int32x4_t horiz_const) {
+  const int8x16_t filters = vcombine_s8(filter, filter);
+
+  uint8x16_t s01 = vcombine_u8(s0, s1);
+  uint8x16_t s23 = vcombine_u8(s2, s3);
+  uint8x16_t s45 = vcombine_u8(s4, s5);
+  uint8x16_t s67 = vcombine_u8(s6, s7);
+
+  int32x4_t sum01 = vusdotq_s32(horiz_const, s01, filters);
+  int32x4_t sum23 = vusdotq_s32(horiz_const, s23, filters);
+  int32x4_t sum45 = vusdotq_s32(horiz_const, s45, filters);
+  int32x4_t sum67 = vusdotq_s32(horiz_const, s67, filters);
+
+  int32x4_t sum0123 = vpaddq_s32(sum01, sum23);
+  int32x4_t sum4567 = vpaddq_s32(sum45, sum67);
+
+  // We halved the filter values so -1 from right shift.
+  return vcombine_s16(vshrn_n_s32(sum0123, ROUND0_BITS - 1),
+                      vshrn_n_s32(sum4567, ROUND0_BITS - 1));
+}
+
+static INLINE void convolve_horiz_scale_neon_i8mm(const uint8_t *src,
+                                                  int src_stride, int16_t *dst,
+                                                  int dst_stride, int w, int h,
+                                                  const int16_t *x_filter,
+                                                  const int subpel_x_qn,
+                                                  const int x_step_qn) {
+  DECLARE_ALIGNED(16, int16_t, temp[8 * 8]);
+  const int bd = 8;
+  // A shim of 1 << (ROUND0_BITS - 1) enables us to use non-rounding
+  // shifts - which are generally faster than rounding shifts on modern CPUs.
+  // Divide the total by 4: we halved the filter values and will use a pairwise
+  // add in the convolution kernel.
+  const int32x4_t horiz_offset = vdupq_n_s32(
+      ((1 << (bd + FILTER_BITS - 1)) + (1 << (ROUND0_BITS - 1))) >> 2);
+
+  if (w == 4) {
+    do {
+      int x_qn = subpel_x_qn;
+
+      // Process a 4x4 tile.
+      for (int r = 0; r < 4; r++) {
+        const uint8_t *const s = &src[x_qn >> SCALE_SUBPEL_BITS];
+
+        const ptrdiff_t filter_offset =
+            SUBPEL_TAPS * ((x_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
+        // Filter values are all even so halve them to fit in int8_t.
+        const int8x8_t filter =
+            vshrn_n_s16(vld1q_s16(x_filter + filter_offset), 1);
+
+        uint8x8_t t0, t1, t2, t3;
+        load_u8_8x4(s, src_stride, &t0, &t1, &t2, &t3);
+
+        int16x4_t d0 = convolve8_4_h(t0, t1, t2, t3, filter, horiz_offset);
+
+        vst1_s16(&temp[r * 4], d0);
+        x_qn += x_step_qn;
+      }
+
+      // Transpose the 4x4 result tile and store.
+      int16x4_t d0, d1, d2, d3;
+      load_s16_4x4(temp, 4, &d0, &d1, &d2, &d3);
+
+      transpose_elems_inplace_s16_4x4(&d0, &d1, &d2, &d3);
+
+      store_s16_4x4(dst, dst_stride, d0, d1, d2, d3);
+
+      dst += 4 * dst_stride;
+      src += 4 * src_stride;
+      h -= 4;
+    } while (h > 0);
+  } else {
+    do {
+      int x_qn = subpel_x_qn;
+      int16_t *d = dst;
+      int width = w;
+
+      do {
+        // Process an 8x8 tile.
+        for (int r = 0; r < 8; r++) {
+          const uint8_t *const s = &src[(x_qn >> SCALE_SUBPEL_BITS)];
+
+          const ptrdiff_t filter_offset =
+              SUBPEL_TAPS * ((x_qn & SCALE_SUBPEL_MASK) >> SCALE_EXTRA_BITS);
+          // Filter values are all even so halve them to fit in int8_t.
+          const int8x8_t filter =
+              vshrn_n_s16(vld1q_s16(x_filter + filter_offset), 1);
+
+          uint8x8_t t0, t1, t2, t3, t4, t5, t6, t7;
+          load_u8_8x8(s, src_stride, &t0, &t1, &t2, &t3, &t4, &t5, &t6, &t7);
+
+          int16x8_t d0 = convolve8_8_h(t0, t1, t2, t3, t4, t5, t6, t7, filter,
+                                       horiz_offset);
+
+          vst1q_s16(&temp[r * 8], d0);
+
+          x_qn += x_step_qn;
+        }
+
+        // Transpose the 8x8 result tile and store.
+        int16x8_t d0, d1, d2, d3, d4, d5, d6, d7;
+        load_s16_8x8(temp, 8, &d0, &d1, &d2, &d3, &d4, &d5, &d6, &d7);
+
+        transpose_elems_inplace_s16_8x8(&d0, &d1, &d2, &d3, &d4, &d5, &d6, &d7);
+
+        store_s16_8x8(d, dst_stride, d0, d1, d2, d3, d4, d5, d6, d7);
+
+        d += 8;
+        width -= 8;
+      } while (width != 0);
+
+      dst += 8 * dst_stride;
+      src += 8 * src_stride;
+      h -= 8;
+    } while (h > 0);
+  }
+}
+
+void av1_convolve_2d_scale_neon_i8mm(const uint8_t *src, int src_stride,
+                                     uint8_t *dst, int dst_stride, int w, int h,
+                                     const InterpFilterParams *filter_params_x,
+                                     const InterpFilterParams *filter_params_y,
+                                     const int subpel_x_qn, const int x_step_qn,
+                                     const int subpel_y_qn, const int y_step_qn,
+                                     ConvolveParams *conv_params) {
+  if (w < 4 || h < 4) {
+    av1_convolve_2d_scale_c(src, src_stride, dst, dst_stride, w, h,
+                            filter_params_x, filter_params_y, subpel_x_qn,
+                            x_step_qn, subpel_y_qn, y_step_qn, conv_params);
+    return;
+  }
+
+  // For the interpolation 8-tap filters are used.
+  assert(filter_params_y->taps <= 8 && filter_params_x->taps <= 8);
+
+  DECLARE_ALIGNED(32, int16_t,
+                  im_block[(2 * MAX_SB_SIZE + MAX_FILTER_TAP) * MAX_SB_SIZE]);
+  int im_h = (((h - 1) * y_step_qn + subpel_y_qn) >> SCALE_SUBPEL_BITS) +
+             filter_params_y->taps;
+  int im_stride = MAX_SB_SIZE;
+  CONV_BUF_TYPE *dst16 = conv_params->dst;
+  const int dst16_stride = conv_params->dst_stride;
+
+  // Account for needing filter_taps / 2 - 1 lines prior and filter_taps / 2
+  // lines post both horizontally and vertically.
+  const ptrdiff_t horiz_offset = filter_params_x->taps / 2 - 1;
+  const ptrdiff_t vert_offset = (filter_params_y->taps / 2 - 1) * src_stride;
+
+  // Horizontal filter
+  convolve_horiz_scale_neon_i8mm(
+      src - horiz_offset - vert_offset, src_stride, im_block, im_stride, w,
+      im_h, filter_params_x->filter_ptr, subpel_x_qn, x_step_qn);
+
+  // Vertical filter
+  if (UNLIKELY(conv_params->is_compound)) {
+    if (conv_params->do_average) {
+      if (conv_params->use_dist_wtd_comp_avg) {
+        compound_dist_wtd_convolve_vert_scale_neon(
+            im_block, im_stride, dst, dst_stride, dst16, dst16_stride, w, h,
+            filter_params_y->filter_ptr, conv_params, subpel_y_qn, y_step_qn);
+      } else {
+        compound_avg_convolve_vert_scale_neon(
+            im_block, im_stride, dst, dst_stride, dst16, dst16_stride, w, h,
+            filter_params_y->filter_ptr, subpel_y_qn, y_step_qn);
+      }
+    } else {
+      compound_convolve_vert_scale_neon(
+          im_block, im_stride, dst16, dst16_stride, w, h,
+          filter_params_y->filter_ptr, subpel_y_qn, y_step_qn);
+    }
+  } else {
+    convolve_vert_scale_neon(im_block, im_stride, dst, dst_stride, w, h,
+                             filter_params_y->filter_ptr, subpel_y_qn,
+                             y_step_qn);
+  }
+}
diff --git a/av1/common/av1_rtcd_defs.pl b/av1/common/av1_rtcd_defs.pl
index f70dce444..e27613a19 100644
--- a/av1/common/av1_rtcd_defs.pl
+++ b/av1/common/av1_rtcd_defs.pl
@@ -606,7 +606,7 @@ ()
   specialize qw/av1_convolve_x_sr_intrabc neon/;
   specialize qw/av1_convolve_y_sr sse2 avx2 neon neon_dotprod neon_i8mm/;
   specialize qw/av1_convolve_y_sr_intrabc neon/;
-  specialize qw/av1_convolve_2d_scale sse4_1 neon neon_dotprod/;
+  specialize qw/av1_convolve_2d_scale sse4_1 neon neon_dotprod neon_i8mm/;
   specialize qw/av1_dist_wtd_convolve_2d ssse3 avx2 neon neon_dotprod neon_i8mm/;
   specialize qw/av1_dist_wtd_convolve_2d_copy sse2 avx2 neon/;
   specialize qw/av1_dist_wtd_convolve_x sse2 avx2 neon neon_dotprod neon_i8mm/;
diff --git a/test/av1_convolve_scale_test.cc b/test/av1_convolve_scale_test.cc
index 2a4bae48b..c7debe27a 100644
--- a/test/av1_convolve_scale_test.cc
+++ b/test/av1_convolve_scale_test.cc
@@ -401,6 +401,13 @@ INSTANTIATE_TEST_SUITE_P(
                        ::testing::ValuesIn(kBlockDim)));
 #endif  // HAVE_NEON_DOTPROD
 
+#if HAVE_NEON_I8MM
+INSTANTIATE_TEST_SUITE_P(
+    NEON_I8MM, LowBDConvolveScaleTest,
+    ::testing::Combine(::testing::Values(av1_convolve_2d_scale_neon_i8mm),
+                       ::testing::ValuesIn(kBlockDim)));
+#endif  // HAVE_NEON_I8MM
+
 #if HAVE_SSE4_1
 INSTANTIATE_TEST_SUITE_P(
     SSE4_1, LowBDConvolveScaleTest,