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Vectorize significant coeff group scanning loop

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This commit is contained in:
Pauli Oikkonen 2018-12-03 17:21:22 +02:00
parent 1bfed73221
commit 584f2f74b6
1 changed files with 38 additions and 17 deletions
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55
src/strategies/avx2/encode_coding_tree-avx2.c
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@ -24,6 +24,7 @@
#include "context.h"
#include "encode_coding_tree-avx2.h"
#include "kvz_math.h"
#include <immintrin.h>
/**
* \brief Encode (X,Y) position of the last significant coefficient
@ -119,6 +120,8 @@ void kvz_encode_coeff_nxn_avx2(encoder_state_t * const state,
kvz_g_sig_last_scan[scan_mode][log2_block_size - 1];
const uint32_t *scan_cg = g_sig_last_scan_cg[log2_block_size - 2][scan_mode];
const __m256i zero = _mm256_set1_epi8(0);
// Init base contexts according to block type
cabac_ctx_t *base_coeff_group_ctx = &(cabac->ctx.cu_sig_coeff_group_model[type]);
cabac_ctx_t *baseCtx = (type == 0) ? &(cabac->ctx.cu_sig_model_luma[0]) :
@ -127,27 +130,45 @@ void kvz_encode_coeff_nxn_avx2(encoder_state_t * const state,
// Scan all coeff groups to find out which of them have coeffs.
// Populate sig_coeffgroup_flag with that info.
unsigned sig_cg_cnt = 0;
for (int cg_y = 0; cg_y < width / 4; ++cg_y) {
for (int cg_x = 0; cg_x < width / 4; ++cg_x) {
unsigned cg_pos = cg_y * width * 4 + cg_x * 4;
for (int coeff_row = 0; coeff_row < 4; ++coeff_row) {
// Load four 16-bit coeffs and see if any of them are non-zero.
unsigned coeff_pos = cg_pos + coeff_row * width;
uint64_t four_coeffs = *(uint64_t*)(&coeff[coeff_pos]);
if (four_coeffs) {
++sig_cg_cnt;
unsigned cg_pos_y = (cg_pos >> log2_block_size) >> TR_MIN_LOG2_SIZE;
unsigned cg_pos_x = (cg_pos & (width - 1)) >> TR_MIN_LOG2_SIZE;
sig_coeffgroup_flag[cg_pos_x + cg_pos_y * num_blk_side] = 1;
break;
}
}
// NOTE: Modified the functionality a bit, sig_coeffgroup_flag used to be
// 1 if true and 0 if false, now it's "undefined but nonzero" if true and
// 0 if false (not actually undefined, it's a bitmask representing the
// significant coefficients' position in the group which in itself could
// be useful information)
uint32_t any_sig_cgs = 0;
for (int32_t cg_y = 0; cg_y < width / 4; ++cg_y) {
for (int32_t cg_x = 0; cg_x < width / 4; ++cg_x) {
uint32_t cg_pos = cg_y * width * 4 + cg_x * 4;
uint32_t cg_pos_y = (cg_pos >> log2_block_size) >> TR_MIN_LOG2_SIZE;
uint32_t cg_pos_x = (cg_pos & (width - 1)) >> TR_MIN_LOG2_SIZE;
__m128d coeffs_d_upper;
__m128d coeffs_d_lower;
__m128i coeffs_upper;
__m128i coeffs_lower;
__m256i cur_coeffs;
coeffs_d_upper = _mm_loadl_pd(coeffs_d_upper, (double *)(coeff + cg_pos + 0 * width));
coeffs_d_upper = _mm_loadh_pd(coeffs_d_upper, (double *)(coeff + cg_pos + 1 * width));
coeffs_d_lower = _mm_loadl_pd(coeffs_d_lower, (double *)(coeff + cg_pos + 2 * width));
coeffs_d_lower = _mm_loadh_pd(coeffs_d_lower, (double *)(coeff + cg_pos + 3 * width));
coeffs_upper = _mm_castpd_si128(coeffs_d_upper);
coeffs_lower = _mm_castpd_si128(coeffs_d_lower);
cur_coeffs = _mm256_insertf128_si256(_mm256_castsi128_si256(coeffs_upper),
coeffs_lower,
1);
__m256i coeffs_zero = _mm256_cmpeq_epi16(cur_coeffs, zero);
uint32_t nz_coeffs_2b = ~((uint32_t)_mm256_movemask_epi8(coeffs_zero));
any_sig_cgs |= nz_coeffs_2b;
sig_coeffgroup_flag[cg_pos_x + cg_pos_y * num_blk_side] = nz_coeffs_2b;
}
}
// Rest of the code assumes at least one non-zero coeff.
assert(sig_cg_cnt > 0);
assert(any_sig_cgs != 0);
// Find the last coeff group by going backwards in scan order.
unsigned scan_cg_last = num_blk_side * num_blk_side - 1;