[x265] [PATCH 4/9] AArch64: Optimise partialButterfly16_neon
Hari Limaye
hari.limaye at arm.com
Thu Aug 22 15:18:57 UTC 2024
Optimise the Neon implementation of partialButterfly16 to process four
lines at a time to make use of the full width of Neon vector registers,
avoiding widening to 32-bit values where possible, and replacing the
addition of a rounding constant with rounding shift instructions.
Relative performance observed compared to the existing implementation:
Neoverse N1: 1.31x
Neoverse V1: 1.69x
Neoverse N2: 1.29x
Neoverse V2: 1.78x
Co-authored-by: Jonathan Wright <jonathan.wright at arm.com>
---
source/common/aarch64/dct-prim.cpp | 142 +++++++++++++++++++----------
1 file changed, 96 insertions(+), 46 deletions(-)
diff --git a/source/common/aarch64/dct-prim.cpp b/source/common/aarch64/dct-prim.cpp
index 778c50100..18d68ba65 100644
--- a/source/common/aarch64/dct-prim.cpp
+++ b/source/common/aarch64/dct-prim.cpp
@@ -250,63 +250,113 @@ uint32_t copy_count_neon(int16_t *coeff, const int16_t *residual, intptr_t resiS
return numSig - vaddvq_s16(vcount);
}
-
-static void partialButterfly16(const int16_t *src, int16_t *dst, int shift, int line)
+template<int shift>
+static void partialButterfly16_neon(const int16_t *src, int16_t *dst)
{
- int j, k;
- int32x4_t E[2], O[2];
- int32x4_t EE, EO;
- int32x2_t EEE, EEO;
- const int add = 1 << (shift - 1);
- const int32x4_t _vadd = {add, 0};
+ const int line = 16;
- for (j = 0; j < line; j++)
+ int16x8_t O[line];
+ int32x4_t EO[line];
+ int32x4_t EEE[line];
+ int32x4_t EEO[line];
+
+ for (int i = 0; i < line; i += 2)
{
- int16x8_t in0 = vld1q_s16(src);
- int16x8_t in1 = rev16(vld1q_s16(src + 8));
+ int16x8_t s0_lo = vld1q_s16(src + i * line);
+ int16x8_t s0_hi = rev16(vld1q_s16(src + i * line + 8));
- E[0] = vaddl_s16(vget_low_s16(in0), vget_low_s16(in1));
- O[0] = vsubl_s16(vget_low_s16(in0), vget_low_s16(in1));
- E[1] = vaddl_high_s16(in0, in1);
- O[1] = vsubl_high_s16(in0, in1);
+ int16x8_t s1_lo = vld1q_s16(src + (i + 1) * line);
+ int16x8_t s1_hi = rev16(vld1q_s16(src + (i + 1) * line + 8));
- for (k = 1; k < 16; k += 2)
- {
- int32x4_t c0 = vmovl_s16(vld1_s16(&g_t16[k][0]));
- int32x4_t c1 = vmovl_s16(vld1_s16(&g_t16[k][4]));
+ int32x4_t E0[2];
+ E0[0] = vaddl_s16(vget_low_s16(s0_lo), vget_low_s16(s0_hi));
+ E0[1] = vaddl_s16(vget_high_s16(s0_lo), vget_high_s16(s0_hi));
- int32x4_t res = _vadd;
- res = vmlaq_s32(res, c0, O[0]);
- res = vmlaq_s32(res, c1, O[1]);
- dst[k * line] = (int16_t)(vaddvq_s32(res) >> shift);
- }
+ int32x4_t E1[2];
+ E1[0] = vaddl_s16(vget_low_s16(s1_lo), vget_low_s16(s1_hi));
+ E1[1] = vaddl_s16(vget_high_s16(s1_lo), vget_high_s16(s1_hi));
- /* EE and EO */
- EE = vaddq_s32(E[0], rev32(E[1]));
- EO = vsubq_s32(E[0], rev32(E[1]));
+ O[i + 0] = vsubq_s16(s0_lo, s0_hi);
+ O[i + 1] = vsubq_s16(s1_lo, s1_hi);
+
+ int32x4_t EE0 = vaddq_s32(E0[0], rev32(E0[1]));
+ int32x4_t EE1 = vaddq_s32(E1[0], rev32(E1[1]));
+ EO[i + 0] = vsubq_s32(E0[0], rev32(E0[1]));
+ EO[i + 1] = vsubq_s32(E1[0], rev32(E1[1]));
+
+ int32x4_t t0 = vreinterpretq_s32_s64(
+ vzip1q_s64(vreinterpretq_s64_s32(EE0), vreinterpretq_s64_s32(EE1)));
+ int32x4_t t1 = vrev64q_s32(vreinterpretq_s32_s64(vzip2q_s64(
+ vreinterpretq_s64_s32(EE0), vreinterpretq_s64_s32(EE1))));
- for (k = 2; k < 16; k += 4)
+
+ EEE[i / 2] = vaddq_s32(t0, t1);
+ EEO[i / 2] = vsubq_s32(t0, t1);
+ }
+
+ for (int i = 0; i < line; i += 4)
+ {
+ for (int k = 1; k < 16; k += 2)
+ {
+ int16x8_t c0_c4 = vld1q_s16(&g_t16[k][0]);
+
+ int32x4_t t0 = vmull_s16(vget_low_s16(c0_c4),
+ vget_low_s16(O[i + 0]));
+ int32x4_t t1 = vmull_s16(vget_low_s16(c0_c4),
+ vget_low_s16(O[i + 1]));
+ int32x4_t t2 = vmull_s16(vget_low_s16(c0_c4),
+ vget_low_s16(O[i + 2]));
+ int32x4_t t3 = vmull_s16(vget_low_s16(c0_c4),
+ vget_low_s16(O[i + 3]));
+ t0 = vmlal_s16(t0, vget_high_s16(c0_c4), vget_high_s16(O[i + 0]));
+ t1 = vmlal_s16(t1, vget_high_s16(c0_c4), vget_high_s16(O[i + 1]));
+ t2 = vmlal_s16(t2, vget_high_s16(c0_c4), vget_high_s16(O[i + 2]));
+ t3 = vmlal_s16(t3, vget_high_s16(c0_c4), vget_high_s16(O[i + 3]));
+
+ int32x4_t t = vpaddq_s32(vpaddq_s32(t0, t1), vpaddq_s32(t2, t3));
+ int16x4_t res = vrshrn_n_s32(t, shift);
+ vst1_s16(dst + k * line, res);
+ }
+
+ for (int k = 2; k < 16; k += 4)
{
int32x4_t c0 = vmovl_s16(vld1_s16(&g_t16[k][0]));
- int32x4_t res = _vadd;
- res = vmlaq_s32(res, c0, EO);
- dst[k * line] = (int16_t)(vaddvq_s32(res) >> shift);
+ int32x4_t t0 = vmulq_s32(c0, EO[i + 0]);
+ int32x4_t t1 = vmulq_s32(c0, EO[i + 1]);
+ int32x4_t t2 = vmulq_s32(c0, EO[i + 2]);
+ int32x4_t t3 = vmulq_s32(c0, EO[i + 3]);
+ int32x4_t t = vpaddq_s32(vpaddq_s32(t0, t1), vpaddq_s32(t2, t3));
+
+ int16x4_t res = vrshrn_n_s32(t, shift);
+ vst1_s16(dst + k * line, res);
}
- /* EEE and EEO */
- EEE[0] = EE[0] + EE[3];
- EEO[0] = EE[0] - EE[3];
- EEE[1] = EE[1] + EE[2];
- EEO[1] = EE[1] - EE[2];
+ int32x4_t c0 = vld1q_s32(t8_even[0]);
+ int32x4_t c4 = vld1q_s32(t8_even[1]);
+ int32x4_t c8 = vld1q_s32(t8_even[2]);
+ int32x4_t c12 = vld1q_s32(t8_even[3]);
- dst[0] = (int16_t)((g_t16[0][0] * EEE[0] + g_t16[0][1] * EEE[1] + add) >> shift);
- dst[8 * line] = (int16_t)((g_t16[8][0] * EEE[0] + g_t16[8][1] * EEE[1] + add) >> shift);
- dst[4 * line] = (int16_t)((g_t16[4][0] * EEO[0] + g_t16[4][1] * EEO[1] + add) >> shift);
- dst[12 * line] = (int16_t)((g_t16[12][0] * EEO[0] + g_t16[12][1] * EEO[1] + add) >> shift);
+ int32x4_t t0 = vpaddq_s32(EEE[i / 2 + 0], EEE[i / 2 + 1]);
+ int32x4_t t1 = vmulq_s32(c0, t0);
+ int16x4_t res0 = vrshrn_n_s32(t1, shift);
+ vst1_s16(dst + 0 * line, res0);
+ int32x4_t t2 = vmulq_s32(c4, EEO[i / 2 + 0]);
+ int32x4_t t3 = vmulq_s32(c4, EEO[i / 2 + 1]);
+ int16x4_t res4 = vrshrn_n_s32(vpaddq_s32(t2, t3), shift);
+ vst1_s16(dst + 4 * line, res4);
- src += 16;
- dst++;
+ int32x4_t t4 = vmulq_s32(c8, EEE[i / 2 + 0]);
+ int32x4_t t5 = vmulq_s32(c8, EEE[i / 2 + 1]);
+ int16x4_t res8 = vrshrn_n_s32(vpaddq_s32(t4, t5), shift);
+ vst1_s16(dst + 8 * line, res8);
+
+ int32x4_t t6 = vmulq_s32(c12, EEO[i / 2 + 0]);
+ int32x4_t t7 = vmulq_s32(c12, EEO[i / 2 + 1]);
+ int16x4_t res12 = vrshrn_n_s32(vpaddq_s32(t6, t7), shift);
+ vst1_s16(dst + 12 * line, res12);
+
+ dst += 4;
}
}
@@ -898,8 +948,8 @@ void dct8_neon(const int16_t *src, int16_t *dst, intptr_t srcStride)
void dct16_neon(const int16_t *src, int16_t *dst, intptr_t srcStride)
{
- const int shift_1st = 3 + X265_DEPTH - 8;
- const int shift_2nd = 10;
+ const int shift_pass1 = 3 + X265_DEPTH - 8;
+ const int shift_pass2 = 10;
ALIGN_VAR_32(int16_t, coef[16 * 16]);
ALIGN_VAR_32(int16_t, block[16 * 16]);
@@ -909,8 +959,8 @@ void dct16_neon(const int16_t *src, int16_t *dst, intptr_t srcStride)
memcpy(&block[i * 16], &src[i * srcStride], 16 * sizeof(int16_t));
}
- partialButterfly16(block, coef, shift_1st, 16);
- partialButterfly16(coef, dst, shift_2nd, 16);
+ partialButterfly16_neon<shift_pass1>(block, coef);
+ partialButterfly16_neon<shift_pass2>(coef, dst);
}
void dct32_neon(const int16_t *src, int16_t *dst, intptr_t srcStride)
--
2.42.1
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