Merge "Un-Revert "Restore vp8_sixtap_predict4x4_neon""

2 files changed, 393 insertions, 3 deletions

diff --git a/vp8/common/arm/neon/sixtappredict_neon.c b/vp8/common/arm/neon/sixtappredict_neon.c
index 622baa3c5..fbb552ebe 100644
--- a/vp8/common/arm/neon/sixtappredict_neon.c
+++ b/vp8/common/arm/neon/sixtappredict_neon.c
@@ -9,6 +9,8 @@
  */
 
 #include <arm_neon.h>
+#include <string.h>
+#include "./vpx_config.h"
 #include "vpx_ports/mem.h"
 
 static const int8_t vp8_sub_pel_filters[8][8] = {
@@ -22,6 +24,396 @@ static const int8_t vp8_sub_pel_filters[8][8] = {
   { 0, -1, 12, 123, -6, 0, 0, 0 },
 };
 
+// This table is derived from vp8/common/filter.c:vp8_sub_pel_filters.
+// Apply abs() to all the values. Elements 0, 2, 3, and 5 are always positive.
+// Elements 1 and 4 are either 0 or negative. The code accounts for this with
+// multiply/accumulates which either add or subtract as needed. The other
+// functions will be updated to use this table later.
+// It is also expanded to 8 elements to allow loading into 64 bit neon
+// registers.
+static const uint8_t abs_filters[8][8] = {
+  { 0, 0, 128, 0, 0, 0, 0, 0 },   { 0, 6, 123, 12, 1, 0, 0, 0 },
+  { 2, 11, 108, 36, 8, 1, 0, 0 }, { 0, 9, 93, 50, 6, 0, 0, 0 },
+  { 3, 16, 77, 77, 16, 3, 0, 0 }, { 0, 6, 50, 93, 9, 0, 0, 0 },
+  { 1, 8, 36, 108, 11, 2, 0, 0 }, { 0, 1, 12, 123, 6, 0, 0, 0 },
+};
+
+static INLINE uint8x8_t load_and_shift(const unsigned char *a) {
+  return vreinterpret_u8_u64(vshl_n_u64(vreinterpret_u64_u8(vld1_u8(a)), 32));
+}
+
+static INLINE void store4x4(unsigned char *dst, int dst_stride,
+                            const uint8x8_t a0, const uint8x8_t a1) {
+  if (!((uintptr_t)dst & 0x3) && !(dst_stride & 0x3)) {
+    vst1_lane_u32((uint32_t *)dst, vreinterpret_u32_u8(a0), 0);
+    dst += dst_stride;
+    vst1_lane_u32((uint32_t *)dst, vreinterpret_u32_u8(a0), 1);
+    dst += dst_stride;
+    vst1_lane_u32((uint32_t *)dst, vreinterpret_u32_u8(a1), 0);
+    dst += dst_stride;
+    vst1_lane_u32((uint32_t *)dst, vreinterpret_u32_u8(a1), 1);
+  } else {
+    // Store to the aligned local buffer and memcpy instead of vget_lane_u8
+    // which is really really slow.
+    uint32_t output_buffer[4];
+    vst1_lane_u32(output_buffer, vreinterpret_u32_u8(a0), 0);
+    vst1_lane_u32(output_buffer + 1, vreinterpret_u32_u8(a0), 1);
+    vst1_lane_u32(output_buffer + 2, vreinterpret_u32_u8(a1), 0);
+    vst1_lane_u32(output_buffer + 3, vreinterpret_u32_u8(a1), 1);
+
+    memcpy(dst, output_buffer, 4);
+    dst += dst_stride;
+    memcpy(dst, output_buffer + 1, 4);
+    dst += dst_stride;
+    memcpy(dst, output_buffer + 2, 4);
+    dst += dst_stride;
+    memcpy(dst, output_buffer + 3, 4);
+  }
+}
+
+static INLINE void filter_add_accumulate(const uint8x16_t a, const uint8x16_t b,
+                                         const uint8x8_t filter, uint16x8_t *c,
+                                         uint16x8_t *d) {
+  const uint32x2x2_t a_shuf = vzip_u32(vreinterpret_u32_u8(vget_low_u8(a)),
+                                       vreinterpret_u32_u8(vget_high_u8(a)));
+  const uint32x2x2_t b_shuf = vzip_u32(vreinterpret_u32_u8(vget_low_u8(b)),
+                                       vreinterpret_u32_u8(vget_high_u8(b)));
+  *c = vmlal_u8(*c, vreinterpret_u8_u32(a_shuf.val[0]), filter);
+  *d = vmlal_u8(*d, vreinterpret_u8_u32(b_shuf.val[0]), filter);
+}
+
+static INLINE void filter_sub_accumulate(const uint8x16_t a, const uint8x16_t b,
+                                         const uint8x8_t filter, uint16x8_t *c,
+                                         uint16x8_t *d) {
+  const uint32x2x2_t a_shuf = vzip_u32(vreinterpret_u32_u8(vget_low_u8(a)),
+                                       vreinterpret_u32_u8(vget_high_u8(a)));
+  const uint32x2x2_t b_shuf = vzip_u32(vreinterpret_u32_u8(vget_low_u8(b)),
+                                       vreinterpret_u32_u8(vget_high_u8(b)));
+  *c = vmlsl_u8(*c, vreinterpret_u8_u32(a_shuf.val[0]), filter);
+  *d = vmlsl_u8(*d, vreinterpret_u8_u32(b_shuf.val[0]), filter);
+}
+
+static INLINE void yonly4x4(const unsigned char *src, int src_stride,
+                            int filter_offset, unsigned char *dst,
+                            int dst_stride) {
+  uint8x8_t a0, a1, a2, a3, a4, a5, a6, a7, a8;
+  uint8x8_t b0, b1, b2, b3, b4, b5, b6, b7, b8;
+  uint16x8_t c0, c1, c2, c3;
+  int16x8_t d0, d1;
+  uint8x8_t e0, e1;
+
+  const uint8x8_t filter = vld1_u8(abs_filters[filter_offset]);
+  const uint8x8_t filter0 = vdup_lane_u8(filter, 0);
+  const uint8x8_t filter1 = vdup_lane_u8(filter, 1);
+  const uint8x8_t filter2 = vdup_lane_u8(filter, 2);
+  const uint8x8_t filter3 = vdup_lane_u8(filter, 3);
+  const uint8x8_t filter4 = vdup_lane_u8(filter, 4);
+  const uint8x8_t filter5 = vdup_lane_u8(filter, 5);
+
+  src -= src_stride * 2;
+  // Shift the even rows to allow using 'vext' to combine the vectors. armv8
+  // has vcopy_lane which would be interesting. This started as just a
+  // horrible workaround for clang adding alignment hints to 32bit loads:
+  // https://llvm.org/bugs/show_bug.cgi?id=24421
+  // But it turns out it almost identical to casting the loads.
+  a0 = load_and_shift(src);
+  src += src_stride;
+  a1 = vld1_u8(src);
+  src += src_stride;
+  a2 = load_and_shift(src);
+  src += src_stride;
+  a3 = vld1_u8(src);
+  src += src_stride;
+  a4 = load_and_shift(src);
+  src += src_stride;
+  a5 = vld1_u8(src);
+  src += src_stride;
+  a6 = load_and_shift(src);
+  src += src_stride;
+  a7 = vld1_u8(src);
+  src += src_stride;
+  a8 = vld1_u8(src);
+
+  // Combine the rows so we can operate on 8 at a time.
+  b0 = vext_u8(a0, a1, 4);
+  b2 = vext_u8(a2, a3, 4);
+  b4 = vext_u8(a4, a5, 4);
+  b6 = vext_u8(a6, a7, 4);
+  b8 = a8;
+
+  // To keep with the 8-at-a-time theme, combine *alternate* rows. This
+  // allows combining the odd rows with the even.
+  b1 = vext_u8(b0, b2, 4);
+  b3 = vext_u8(b2, b4, 4);
+  b5 = vext_u8(b4, b6, 4);
+  b7 = vext_u8(b6, b8, 4);
+
+  // Multiply and expand to 16 bits.
+  c0 = vmull_u8(b0, filter0);
+  c1 = vmull_u8(b2, filter0);
+  c2 = vmull_u8(b5, filter5);
+  c3 = vmull_u8(b7, filter5);
+
+  // Multiply, subtract and accumulate for filters 1 and 4 (the negative
+  // ones).
+  c0 = vmlsl_u8(c0, b4, filter4);
+  c1 = vmlsl_u8(c1, b6, filter4);
+  c2 = vmlsl_u8(c2, b1, filter1);
+  c3 = vmlsl_u8(c3, b3, filter1);
+
+  // Add more positive ones. vmlal should really return a signed type.
+  // It's doing signed math internally, as evidenced by the fact we can do
+  // subtractions followed by more additions. Ideally we could use
+  // vqmlal/sl but that instruction doesn't exist. Might be able to
+  // shoehorn vqdmlal/vqdmlsl in here but it would take some effort.
+  c0 = vmlal_u8(c0, b2, filter2);
+  c1 = vmlal_u8(c1, b4, filter2);
+  c2 = vmlal_u8(c2, b3, filter3);
+  c3 = vmlal_u8(c3, b5, filter3);
+
+  // Use signed saturation math because vmlsl may have left some negative
+  // numbers in there.
+  d0 = vqaddq_s16(vreinterpretq_s16_u16(c2), vreinterpretq_s16_u16(c0));
+  d1 = vqaddq_s16(vreinterpretq_s16_u16(c3), vreinterpretq_s16_u16(c1));
+
+  // Use signed again because numbers like -200 need to be saturated to 0.
+  e0 = vqrshrun_n_s16(d0, 7);
+  e1 = vqrshrun_n_s16(d1, 7);
+
+  store4x4(dst, dst_stride, e0, e1);
+}
+
+void vp8_sixtap_predict4x4_neon(unsigned char *src_ptr, int src_pixels_per_line,
+                                int xoffset, int yoffset,
+                                unsigned char *dst_ptr, int dst_pitch) {
+  uint8x16_t s0, s1, s2, s3, s4;
+  uint64x2_t s01, s23;
+  // Variables to hold src[] elements for the given filter[]
+  uint8x8_t s0_f5, s1_f5, s2_f5, s3_f5, s4_f5;
+  uint8x8_t s4_f1, s4_f2, s4_f3, s4_f4;
+  uint8x16_t s01_f0, s23_f0;
+  uint64x2_t s01_f3, s23_f3;
+  uint32x2x2_t s01_f3_q, s23_f3_q, s01_f5_q, s23_f5_q;
+  // Accumulator variables.
+  uint16x8_t d0123, d4567, d89;
+  uint16x8_t d0123_a, d4567_a, d89_a;
+  int16x8_t e0123, e4567, e89;
+  // Second pass intermediates.
+  uint8x8_t b0, b1, b2, b3, b4, b5, b6, b7, b8;
+  uint16x8_t c0, c1, c2, c3;
+  int16x8_t d0, d1;
+  uint8x8_t e0, e1;
+  uint8x8_t filter, filter0, filter1, filter2, filter3, filter4, filter5;
+
+  if (xoffset == 0) {  // Second pass only.
+    yonly4x4(src_ptr, src_pixels_per_line, yoffset, dst_ptr, dst_pitch);
+    return;
+  }
+
+  if (yoffset == 0) {  // First pass only.
+    src_ptr -= 2;
+  } else {  // Add context for the second pass. 2 extra lines on top.
+    src_ptr -= 2 + (src_pixels_per_line * 2);
+  }
+
+  filter = vld1_u8(abs_filters[xoffset]);
+  filter0 = vdup_lane_u8(filter, 0);
+  filter1 = vdup_lane_u8(filter, 1);
+  filter2 = vdup_lane_u8(filter, 2);
+  filter3 = vdup_lane_u8(filter, 3);
+  filter4 = vdup_lane_u8(filter, 4);
+  filter5 = vdup_lane_u8(filter, 5);
+
+  // 2 bytes of context, 4 bytes of src values, 3 bytes of context, 7 bytes of
+  // garbage. So much effort for that last single bit.
+  // The low values of each pair are for filter0.
+  s0 = vld1q_u8(src_ptr);
+  src_ptr += src_pixels_per_line;
+  s1 = vld1q_u8(src_ptr);
+  src_ptr += src_pixels_per_line;
+  s2 = vld1q_u8(src_ptr);
+  src_ptr += src_pixels_per_line;
+  s3 = vld1q_u8(src_ptr);
+  src_ptr += src_pixels_per_line;
+
+  // Shift to extract values for filter[5]
+  // If src[] is 0, this puts:
+  // 3 4 5 6 7 8 9 10 in s0_f5
+  // Can't use vshr.u64 because it crosses the double word boundary.
+  s0_f5 = vext_u8(vget_low_u8(s0), vget_high_u8(s0), 5);
+  s1_f5 = vext_u8(vget_low_u8(s1), vget_high_u8(s1), 5);
+  s2_f5 = vext_u8(vget_low_u8(s2), vget_high_u8(s2), 5);
+  s3_f5 = vext_u8(vget_low_u8(s3), vget_high_u8(s3), 5);
+
+  s01_f0 = vcombine_u8(vget_low_u8(s0), vget_low_u8(s1));
+  s23_f0 = vcombine_u8(vget_low_u8(s2), vget_low_u8(s3));
+
+  s01_f5_q = vzip_u32(vreinterpret_u32_u8(s0_f5), vreinterpret_u32_u8(s1_f5));
+  s23_f5_q = vzip_u32(vreinterpret_u32_u8(s2_f5), vreinterpret_u32_u8(s3_f5));
+  d0123 = vmull_u8(vreinterpret_u8_u32(s01_f5_q.val[0]), filter5);
+  d4567 = vmull_u8(vreinterpret_u8_u32(s23_f5_q.val[0]), filter5);
+
+  // Keep original src data as 64 bits to simplify shifting and extracting.
+  s01 = vreinterpretq_u64_u8(s01_f0);
+  s23 = vreinterpretq_u64_u8(s23_f0);
+
+  // 3 4 5 6 * filter0
+  filter_add_accumulate(s01_f0, s23_f0, filter0, &d0123, &d4567);
+
+  // Shift over one to use -1, 0, 1, 2 for filter1
+  // -1 0 1 2 * filter1
+  filter_sub_accumulate(vreinterpretq_u8_u64(vshrq_n_u64(s01, 8)),
+                        vreinterpretq_u8_u64(vshrq_n_u64(s23, 8)), filter1,
+                        &d0123, &d4567);
+
+  // 2 3 4 5 * filter4
+  filter_sub_accumulate(vreinterpretq_u8_u64(vshrq_n_u64(s01, 32)),
+                        vreinterpretq_u8_u64(vshrq_n_u64(s23, 32)), filter4,
+                        &d0123, &d4567);
+
+  // 0 1 2 3 * filter2
+  filter_add_accumulate(vreinterpretq_u8_u64(vshrq_n_u64(s01, 16)),
+                        vreinterpretq_u8_u64(vshrq_n_u64(s23, 16)), filter2,
+                        &d0123, &d4567);
+
+  // 1 2 3 4 * filter3
+  s01_f3 = vshrq_n_u64(s01, 24);
+  s23_f3 = vshrq_n_u64(s23, 24);
+  s01_f3_q = vzip_u32(vreinterpret_u32_u64(vget_low_u64(s01_f3)),
+                      vreinterpret_u32_u64(vget_high_u64(s01_f3)));
+  s23_f3_q = vzip_u32(vreinterpret_u32_u64(vget_low_u64(s23_f3)),
+                      vreinterpret_u32_u64(vget_high_u64(s23_f3)));
+  // Accumulate into different registers so it can use saturated addition.
+  d0123_a = vmull_u8(vreinterpret_u8_u32(s01_f3_q.val[0]), filter3);
+  d4567_a = vmull_u8(vreinterpret_u8_u32(s23_f3_q.val[0]), filter3);
+
+  e0123 =
+      vqaddq_s16(vreinterpretq_s16_u16(d0123), vreinterpretq_s16_u16(d0123_a));
+  e4567 =
+      vqaddq_s16(vreinterpretq_s16_u16(d4567), vreinterpretq_s16_u16(d4567_a));
+
+  // Shift and narrow.
+  b0 = vqrshrun_n_s16(e0123, 7);
+  b2 = vqrshrun_n_s16(e4567, 7);
+
+  if (yoffset == 0) {  // firstpass_filter4x4_only
+    store4x4(dst_ptr, dst_pitch, b0, b2);
+    return;
+  }
+
+  // Load additional context when doing both filters.
+  s0 = vld1q_u8(src_ptr);
+  src_ptr += src_pixels_per_line;
+  s1 = vld1q_u8(src_ptr);
+  src_ptr += src_pixels_per_line;
+  s2 = vld1q_u8(src_ptr);
+  src_ptr += src_pixels_per_line;
+  s3 = vld1q_u8(src_ptr);
+  src_ptr += src_pixels_per_line;
+  s4 = vld1q_u8(src_ptr);
+
+  s0_f5 = vext_u8(vget_low_u8(s0), vget_high_u8(s0), 5);
+  s1_f5 = vext_u8(vget_low_u8(s1), vget_high_u8(s1), 5);
+  s2_f5 = vext_u8(vget_low_u8(s2), vget_high_u8(s2), 5);
+  s3_f5 = vext_u8(vget_low_u8(s3), vget_high_u8(s3), 5);
+  s4_f5 = vext_u8(vget_low_u8(s4), vget_high_u8(s4), 5);
+
+  // 3 4 5 6 * filter0
+  s01_f0 = vcombine_u8(vget_low_u8(s0), vget_low_u8(s1));
+  s23_f0 = vcombine_u8(vget_low_u8(s2), vget_low_u8(s3));
+
+  s01_f5_q = vzip_u32(vreinterpret_u32_u8(s0_f5), vreinterpret_u32_u8(s1_f5));
+  s23_f5_q = vzip_u32(vreinterpret_u32_u8(s2_f5), vreinterpret_u32_u8(s3_f5));
+  // But this time instead of 16 pixels to filter, there are 20. So an extra
+  // run with a doubleword register.
+  d0123 = vmull_u8(vreinterpret_u8_u32(s01_f5_q.val[0]), filter5);
+  d4567 = vmull_u8(vreinterpret_u8_u32(s23_f5_q.val[0]), filter5);
+  d89 = vmull_u8(s4_f5, filter5);
+
+  // Save a copy as u64 for shifting.
+  s01 = vreinterpretq_u64_u8(s01_f0);
+  s23 = vreinterpretq_u64_u8(s23_f0);
+
+  filter_add_accumulate(s01_f0, s23_f0, filter0, &d0123, &d4567);
+  d89 = vmlal_u8(d89, vget_low_u8(s4), filter0);
+
+  filter_sub_accumulate(vreinterpretq_u8_u64(vshrq_n_u64(s01, 8)),
+                        vreinterpretq_u8_u64(vshrq_n_u64(s23, 8)), filter1,
+                        &d0123, &d4567);
+  s4_f1 = vext_u8(vget_low_u8(s4), vget_high_u8(s4), 1);
+  d89 = vmlsl_u8(d89, s4_f1, filter1);
+
+  filter_sub_accumulate(vreinterpretq_u8_u64(vshrq_n_u64(s01, 32)),
+                        vreinterpretq_u8_u64(vshrq_n_u64(s23, 32)), filter4,
+                        &d0123, &d4567);
+  s4_f4 = vext_u8(vget_low_u8(s4), vget_high_u8(s4), 4);
+  d89 = vmlsl_u8(d89, s4_f4, filter4);
+
+  filter_add_accumulate(vreinterpretq_u8_u64(vshrq_n_u64(s01, 16)),
+                        vreinterpretq_u8_u64(vshrq_n_u64(s23, 16)), filter2,
+                        &d0123, &d4567);
+  s4_f2 = vext_u8(vget_low_u8(s4), vget_high_u8(s4), 2);
+  d89 = vmlal_u8(d89, s4_f2, filter2);
+
+  s01_f3 = vshrq_n_u64(s01, 24);
+  s23_f3 = vshrq_n_u64(s23, 24);
+  s01_f3_q = vzip_u32(vreinterpret_u32_u64(vget_low_u64(s01_f3)),
+                      vreinterpret_u32_u64(vget_high_u64(s01_f3)));
+  s23_f3_q = vzip_u32(vreinterpret_u32_u64(vget_low_u64(s23_f3)),
+                      vreinterpret_u32_u64(vget_high_u64(s23_f3)));
+  s4_f3 = vext_u8(vget_low_u8(s4), vget_high_u8(s4), 3);
+  d0123_a = vmull_u8(vreinterpret_u8_u32(s01_f3_q.val[0]), filter3);
+  d4567_a = vmull_u8(vreinterpret_u8_u32(s23_f3_q.val[0]), filter3);
+  d89_a = vmull_u8(s4_f3, filter3);
+
+  e0123 =
+      vqaddq_s16(vreinterpretq_s16_u16(d0123), vreinterpretq_s16_u16(d0123_a));
+  e4567 =
+      vqaddq_s16(vreinterpretq_s16_u16(d4567), vreinterpretq_s16_u16(d4567_a));
+  e89 = vqaddq_s16(vreinterpretq_s16_u16(d89), vreinterpretq_s16_u16(d89_a));
+
+  b4 = vqrshrun_n_s16(e0123, 7);
+  b6 = vqrshrun_n_s16(e4567, 7);
+  b8 = vqrshrun_n_s16(e89, 7);
+
+  // Second pass: 4x4
+  filter = vld1_u8(abs_filters[yoffset]);
+  filter0 = vdup_lane_u8(filter, 0);
+  filter1 = vdup_lane_u8(filter, 1);
+  filter2 = vdup_lane_u8(filter, 2);
+  filter3 = vdup_lane_u8(filter, 3);
+  filter4 = vdup_lane_u8(filter, 4);
+  filter5 = vdup_lane_u8(filter, 5);
+
+  b1 = vext_u8(b0, b2, 4);
+  b3 = vext_u8(b2, b4, 4);
+  b5 = vext_u8(b4, b6, 4);
+  b7 = vext_u8(b6, b8, 4);
+
+  c0 = vmull_u8(b0, filter0);
+  c1 = vmull_u8(b2, filter0);
+  c2 = vmull_u8(b5, filter5);
+  c3 = vmull_u8(b7, filter5);
+
+  c0 = vmlsl_u8(c0, b4, filter4);
+  c1 = vmlsl_u8(c1, b6, filter4);
+  c2 = vmlsl_u8(c2, b1, filter1);
+  c3 = vmlsl_u8(c3, b3, filter1);
+
+  c0 = vmlal_u8(c0, b2, filter2);
+  c1 = vmlal_u8(c1, b4, filter2);
+  c2 = vmlal_u8(c2, b3, filter3);
+  c3 = vmlal_u8(c3, b5, filter3);
+
+  d0 = vqaddq_s16(vreinterpretq_s16_u16(c2), vreinterpretq_s16_u16(c0));
+  d1 = vqaddq_s16(vreinterpretq_s16_u16(c3), vreinterpretq_s16_u16(c1));
+
+  e0 = vqrshrun_n_s16(d0, 7);
+  e1 = vqrshrun_n_s16(d1, 7);
+
+  store4x4(dst_ptr, dst_pitch, e0, e1);
+}
+
 void vp8_sixtap_predict8x4_neon(unsigned char *src_ptr, int src_pixels_per_line,
                                 int xoffset, int yoffset,
                                 unsigned char *dst_ptr, int dst_pitch) {
diff --git a/vp8/common/rtcd_defs.pl b/vp8/common/rtcd_defs.pl
index 8dc36f731..5d8e4a78d 100644
--- a/vp8/common/rtcd_defs.pl
+++ b/vp8/common/rtcd_defs.pl
@@ -173,10 +173,8 @@ add_proto qw/void vp8_sixtap_predict8x4/, "unsigned char *src, int src_pitch, in
 specialize qw/vp8_sixtap_predict8x4 mmx sse2 ssse3 neon dspr2 msa/;
 $vp8_sixtap_predict8x4_dspr2=vp8_sixtap_predict8x4_dspr2;
 
-# TODO(johannkoenig): Add neon implementation
-# https://bugs.chromium.org/p/webm/issues/detail?id=1273
 add_proto qw/void vp8_sixtap_predict4x4/, "unsigned char *src, int src_pitch, int xofst, int yofst, unsigned char *dst, int dst_pitch";
-specialize qw/vp8_sixtap_predict4x4 mmx ssse3 dspr2 msa/;
+specialize qw/vp8_sixtap_predict4x4 mmx ssse3 neon dspr2 msa/;
 $vp8_sixtap_predict4x4_dspr2=vp8_sixtap_predict4x4_dspr2;
 
 add_proto qw/void vp8_bilinear_predict16x16/, "unsigned char *src, int src_pitch, int xofst, int yofst, unsigned char *dst, int dst_pitch";