get_rows & dequantize function implementation for repacked weights of type q6_K (q6_Kx8)

ggml/src/ggml-cpu/repack.cpp

@@ -1576,6 +1576,11 @@ template <typename BLOC_TYPE, int64_t INTER_SIZE, int64_t NB_COLS, ggml_type PAR
 
                     size += sizeof_mmid_row_mapping*ne02*(ne12 + 1);
 
+                    return true;
+                }
+            case GGML_OP_GET_ROWS:
+                {
+                    size = 0;
                     return true;
                 }
             default:
@@ -1593,6 +1598,9 @@ template <typename BLOC_TYPE, int64_t INTER_SIZE, int64_t NB_COLS, ggml_type PAR
             case GGML_OP_MUL_MAT_ID:
                 forward_mul_mat_id(params, op);
                 return true;
+            case GGML_OP_GET_ROWS:
+                forward_get_rows(params, op);
+                return true;
             default:
                 // GGML_ABORT("fatal error");
                 break;
@@ -1801,6 +1809,155 @@ template <typename BLOC_TYPE, int64_t INTER_SIZE, int64_t NB_COLS, ggml_type PAR
 #undef MMID_MATRIX_ROW
     }
 
+     void forward_get_rows(const ggml_compute_params * params, ggml_tensor * dst) {
+        const ggml_tensor * src0 = dst->src[0];
+
+        switch (src0->type) {
+            case GGML_TYPE_Q6_K:
+                ggml_compute_forward_get_rows_q6_Kx8(params, dst);
+                break;
+            default:
+                GGML_ABORT("fatal error");
+                break;
+        }
+    }
+
+    static void ggml_compute_forward_get_rows_q6_Kx8(const ggml_compute_params * params, ggml_tensor * dst) {
+
+        const ggml_tensor * src0 = dst->src[0];
+        const ggml_tensor * src1 = dst->src[1];
+
+        GGML_TENSOR_BINARY_OP_LOCALS
+        const int64_t nc = ne00;
+        const int64_t nr = ggml_nelements(src1);
+
+        assert(ne0 == nc);
+        assert(ne02 == ne11);
+        assert(nb00 == ggml_type_size(src0->type));
+        assert(ggml_nrows(dst) == nr);
+
+        const int ith = params->ith;
+        const int nth = params->nth;
+
+        // rows per thread
+        const int dr = (nr + nth - 1) / nth;
+
+        // row range for this thread
+        const int ir0 = dr * ith;
+        const int ir1 = MIN(ir0 + dr, nr);
+
+        constexpr int nrows_interleaved = 8;
+        const size_t sizeof_one_repacked_block = sizeof(block_q6_Kx8);
+
+        const int num_repacked_blocks_per_row_width = nc / QK_K;
+
+        const size_t stride_between_actual_row_groups = num_repacked_blocks_per_row_width * sizeof_one_repacked_block;
+
+        for (int64_t i = ir0; i < ir1; ++i) {
+            const int64_t i12 = i / (ne11 * ne10);
+            const int64_t i11 = (i - i12 * ne11 * ne10) / ne10;
+            const int64_t i10 = (i - i12 * ne11 * ne10 - i11 * ne10);
+            const int64_t i01 = *(int32_t *)((char *)src1->data + i10 * nb10 + i11 * nb11 + i12 * nb12);  // original logical row
+
+            GGML_ASSERT(i01 >= 0 && i01 < ne01);
+
+            const int row_group_idx = i01 / nrows_interleaved;
+            const int row_idx_in_group = i01 % nrows_interleaved;
+
+            const char * base_ptr_for_higher_dims_in_src0 = (const char *)src0->data + i11 * nb02 + i12 * nb03;
+
+            // Pointer to the first block_q6_Kx8 of the identified row_group_idx
+            const block_q6_Kx8 * p_first_repacked_block_of_group_x8 = (const block_q6_Kx8 *)(base_ptr_for_higher_dims_in_src0 + row_group_idx * stride_between_actual_row_groups);
+
+            dequantize_row_q6_Kx8(
+                p_first_repacked_block_of_group_x8,
+                (float *)((char *)dst->data + i10 * nb1 + i11 * nb2 + i12 * nb3), nc, row_idx_in_group);
+        }
+    }
+
+
+     /**
+     * Dequantizes a single logical row from data repacked with quant interleaving for repacked block_q6_Kx8
+     *
+     * @param p_repacked_group_column_blocks Pointer to the start of 'block_q6_Kx8' for the row group.
+     * @param y                              Output buffer for the dequantized float values.
+     * @param k                              Total number of elements (columns) in the logical row.
+     * @param row_idx_in_group               Index (0-7) of the logical row to dequantize.
+     */
+
+    static void dequantize_row_q6_Kx8(
+        const void * GGML_RESTRICT p_repacked_blocks,
+        float * GGML_RESTRICT y,
+        int64_t k,
+        int row_idx_in_group) {
+
+        assert(k % QK_K == 0);
+        assert(row_idx_in_group >= 0 && row_idx_in_group < 8);
+
+        const int nb = k / QK_K;
+        const block_q6_Kx8 * blocks = (const block_q6_Kx8 *)p_repacked_blocks;
+
+        for (int i = 0; i < nb; i++) {
+            const block_q6_Kx8 * current_block = &blocks[i];
+
+            const float d_super_block = GGML_FP16_TO_FP32(current_block->d[row_idx_in_group]);
+
+            const uint8_t * ptr_ql_base = current_block->ql;
+            const uint8_t * ptr_qh_base = current_block->qh;
+            uint8_t * ptr_repacked_scales = (uint8_t *) current_block->scales; // 16 * 8 scales repacked
+            for (int n = 0; n < QK_K; n += 128) {
+                for (int l = 0; l < 32; ++l) {
+                    int is = l/16;
+
+                    // get the 4 scales needed for q1, q2, q3 and q4
+                    const int8_t sc0 = read_scale_from_repacked(ptr_repacked_scales, row_idx_in_group, is + 0);
+                    const int8_t sc1 = read_scale_from_repacked(ptr_repacked_scales, row_idx_in_group, is + 2);
+                    const int8_t sc2 = read_scale_from_repacked(ptr_repacked_scales, row_idx_in_group, is + 4);
+                    const int8_t sc3 = read_scale_from_repacked(ptr_repacked_scales, row_idx_in_group, is + 6);
+
+                    // get the right ql & qh values from the interleaved data
+                    const uint8_t ql_l0  = read_ql_qh_from_repacked(ptr_ql_base, row_idx_in_group, n/2 + l +  0);
+                    const uint8_t ql_l32 = read_ql_qh_from_repacked(ptr_ql_base, row_idx_in_group, n/2 + l + 32);
+                    const uint8_t qh_l   = read_ql_qh_from_repacked(ptr_qh_base, row_idx_in_group, n/4 + l);
+
+                    const int8_t q1 = (int8_t) ((ql_l0 & 0xF) | (((qh_l >> 0) & 3) << 4)) - 32;
+                    const int8_t q2 = (int8_t) ((ql_l32 & 0xF) | (((qh_l >> 2) & 3) << 4)) - 32;
+                    const int8_t q3 = (int8_t) ((ql_l0  >> 4) | (((qh_l >> 4) & 3) << 4)) - 32;
+                    const int8_t q4 = (int8_t) ((ql_l32  >> 4) | (((qh_l >> 6) & 3) << 4)) - 32;
+
+                    y[l] = d_super_block * sc0 * q1;
+                    y[l + 32] = d_super_block * sc1 * q2;
+                    y[l + 64] = d_super_block * sc2 * q3;
+                    y[l + 96] = d_super_block * sc3 * q4;
+                }
+                y  += 128;
+               ptr_repacked_scales = (uint8_t *) current_block->scales + 64;
+            }
+        }
+    }
+
+
+     /**
+     * Read the scales from the repacked ptr_repacked_scales
+     */
+    static inline int8_t read_scale_from_repacked(const uint8_t* ptr_repacked_scales, int row_idx_in_group, int scale_idx) {
+        const int pair_group_idx = scale_idx / 2;
+        const int sub_idx_in_pair = scale_idx % 2;
+        const int offset = pair_group_idx * 16 + row_idx_in_group * 2 + sub_idx_in_pair;
+        return ptr_repacked_scales[offset];
+    }
+
+    /**
+     * Read the qh / ql from the repacked ptr_qh_ql_base
+     */
+    static inline uint8_t read_ql_qh_from_repacked(const uint8_t* ptr_qh_ql_base, int row_idx_in_group, int ql_0_idx) {
+        const int block_size_interleave  = 8;
+        const int chunk_idx = ql_0_idx / block_size_interleave;
+        const int offset_in_chunk = ql_0_idx % block_size_interleave;
+        const int offset = chunk_idx * (8 * block_size_interleave) + row_idx_in_group * block_size_interleave + offset_in_chunk;
+        return ptr_qh_ql_base[offset];
+    }
+
     int repack(struct ggml_tensor * t, const void * data, size_t data_size) override {
         GGML_LOG_DEBUG("%s: repack tensor %s with %s_%dx%d\n", __func__, t->name, ggml_type_name(t->type),
                        (int) NB_COLS, (int) INTER_SIZE);
@@ -1949,12 +2106,23 @@ class extra_buffer_type : ggml::cpu::extra_buffer_type {
             //if (op->src[1]->type == GGML_TYPE_Q8_0) {
             //    return true;
             //}
+        } else if (op->op == GGML_OP_GET_ROWS
+        && op->src[0]->buffer
+        && (ggml_n_dims(op->src[0]) == 2)
+        && op->src[0]->buffer->buft == ggml_backend_cpu_repack_buffer_type()
+        && ggml_repack_get_optimal_repack_type(op->src[0])) {
+        if (op->src[1]->buffer && !ggml_backend_buft_is_host(op->src[1]->buffer->buft)) {
+            return false;
+        }
+        if (op->src[0]->type == GGML_TYPE_Q6_K) {
+            return true;
+        }
         }
         return false;
     }
 
     ggml::cpu::tensor_traits * get_tensor_traits(const struct ggml_tensor * op) override {
-        if (op->op == GGML_OP_MUL_MAT || op->op == GGML_OP_MUL_MAT_ID) {
+        if (op->op == GGML_OP_MUL_MAT || op->op == GGML_OP_MUL_MAT_ID || op->op == GGML_OP_GET_ROWS) {
             if (op->src[0]->buffer && op->src[0]->buffer->buft == ggml_backend_cpu_repack_buffer_type()) {
                 return (ggml::cpu::tensor_traits *) op->src[0]->extra;
             }