correctly implement softmax backward pass using new operation ggml_diag
ggml_diag constructs diagonal matrices with entries. ggml_diag(shape[a,1,c,d]) -> shape[a,a,c,d]
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2 changed files with 137 additions and 14 deletions
146
ggml.c
146
ggml.c
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@ -3991,6 +3991,7 @@ static const char * GGML_OP_LABEL[GGML_OP_COUNT] = {
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"TRANSPOSE",
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"GET_ROWS",
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"GET_ROWS_BACK",
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"DIAG",
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"DIAG_MASK_INF",
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"DIAG_MASK_ZERO",
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"SOFT_MAX",
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@ -4007,7 +4008,7 @@ static const char * GGML_OP_LABEL[GGML_OP_COUNT] = {
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"MAP_BINARY",
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};
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static_assert(GGML_OP_COUNT == 45, "GGML_OP_COUNT != 45");
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static_assert(GGML_OP_COUNT == 46, "GGML_OP_COUNT != 46");
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static const char * GGML_OP_SYMBOL[GGML_OP_COUNT] = {
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"none",
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@ -4047,6 +4048,7 @@ static const char * GGML_OP_SYMBOL[GGML_OP_COUNT] = {
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"transpose(x)",
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"get_rows(x)",
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"get_rows_back(x)",
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"diag(x)",
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"diag_mask_inf(x)",
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"diag_mask_zero(x)",
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"soft_max(x)",
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@ -4063,7 +4065,7 @@ static const char * GGML_OP_SYMBOL[GGML_OP_COUNT] = {
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"f(x,y)",
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};
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static_assert(GGML_OP_COUNT == 45, "GGML_OP_COUNT != 45");
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static_assert(GGML_OP_COUNT == 46, "GGML_OP_COUNT != 46");
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static_assert(sizeof(struct ggml_object)%GGML_MEM_ALIGN == 0, "ggml_object size must be a multiple of GGML_MEM_ALIGN");
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static_assert(sizeof(struct ggml_tensor)%GGML_MEM_ALIGN == 0, "ggml_tensor size must be a multiple of GGML_MEM_ALIGN");
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@ -6175,6 +6177,30 @@ struct ggml_tensor * ggml_get_rows_back(
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return result;
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}
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// ggml_diag
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struct ggml_tensor * ggml_diag(
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struct ggml_context * ctx,
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struct ggml_tensor * a) {
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GGML_ASSERT(a->ne[1] == 1);
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bool is_node = false;
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if (a->grad) {
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is_node = true;
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}
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const int64_t ne[4] = { a->ne[0], a->ne[0], a->ne[2], a->ne[3] };
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struct ggml_tensor * result = ggml_new_tensor(ctx, a->type, MAX(a->n_dims, 2), ne);
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result->op = GGML_OP_DIAG;
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result->grad = is_node ? ggml_dup_tensor(ctx, result) : NULL;
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result->src0 = a;
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result->src1 = NULL;
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return result;
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}
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// ggml_diag_mask_inf
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struct ggml_tensor * ggml_diag_mask_inf_impl(
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@ -10269,6 +10295,79 @@ static void ggml_compute_forward_get_rows_back(
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//}
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}
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// ggml_compute_forward_diag
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static void ggml_compute_forward_diag_f32(
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const struct ggml_compute_params * params,
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const struct ggml_tensor * src0,
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struct ggml_tensor * dst) {
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assert(params->ith == 0);
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if (params->type == GGML_TASK_INIT || params->type == GGML_TASK_FINALIZE) {
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return;
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}
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// TODO: handle transposed/permuted matrices
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const int ne00 = src0->ne[0];
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const int ne01 = src0->ne[1];
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const int ne02 = src0->ne[2];
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const int ne03 = src0->ne[3];
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const int ne0 = dst->ne[0];
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const int ne1 = dst->ne[1];
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const int ne2 = dst->ne[2];
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const int ne3 = dst->ne[3];
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assert(ne00 == ne0);
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assert(ne00 == ne1);
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assert(ne01 == 1);
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assert(ne02 == ne2);
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assert(ne03 == ne3);
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const int nb00 = src0->nb[0];
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const int nb01 = src0->nb[1];
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const int nb02 = src0->nb[2];
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const int nb03 = src0->nb[3];
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const int nb0 = dst->nb[0];
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const int nb1 = dst->nb[1];
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const int nb2 = dst->nb[2];
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const int nb3 = dst->nb[3];
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assert(nb00 == sizeof(float));
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assert(nb0 == sizeof(float));
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for (int i3 = 0; i3 < ne3; i3++) {
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for (int i2 = 0; i2 < ne2; i2++) {
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for (int i1 = 0; i1 < ne1; i1++) {
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float * d = (float *)((char *) dst->data + i3*nb3 + i2*nb2 + i1*nb1);
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float * s = (float *)((char *) src0->data + i3*nb03 + i2*nb02);
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for (int i0 = 0; i0 < i1; i0++) {
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d[i0] = 0;
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}
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d[i1] = s[i1];
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for (int i0 = i1+1; i0 < ne0; i0++) {
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d[i0] = 0;
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}
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}
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}
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}
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}
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static void ggml_compute_forward_diag(
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const struct ggml_compute_params * params,
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const struct ggml_tensor * src0,
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struct ggml_tensor * dst) {
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switch (src0->type) {
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case GGML_TYPE_F32:
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{
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ggml_compute_forward_diag_f32(params, src0, dst);
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} break;
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default:
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{
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GGML_ASSERT(false);
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} break;
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}
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}
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// ggml_compute_forward_diag_mask_inf
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static void ggml_compute_forward_diag_mask_f32(
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@ -10392,7 +10491,7 @@ static void ggml_compute_forward_soft_max_f32(
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if (sp[i] == -INFINITY) {
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dp[i] = 0.0f;
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} else {
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//const float val = (p[i] == -INFINITY) ? 0.0 : exp(p[i] - max);
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// const float val = (sp[i] == -INFINITY) ? 0.0 : exp(sp[i] - max);
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ggml_fp16_t s = GGML_FP32_TO_FP16(sp[i] - max);
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memcpy(&scvt, &s, sizeof(scvt));
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const float val = GGML_FP16_TO_FP32(table_exp_f16[scvt]);
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@ -12443,6 +12542,10 @@ static void ggml_compute_forward(struct ggml_compute_params * params, struct ggm
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{
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ggml_compute_forward_get_rows_back(params, tensor->src0, tensor->src1, tensor);
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} break;
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case GGML_OP_DIAG:
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{
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ggml_compute_forward_diag(params, tensor->src0, tensor);
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} break;
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case GGML_OP_DIAG_MASK_INF:
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{
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ggml_compute_forward_diag_mask_inf(params, tensor->src0, tensor->src1, tensor);
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@ -12906,6 +13009,10 @@ static void ggml_compute_backward(struct ggml_context * ctx, struct ggml_tensor
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// noop
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}
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} break;
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case GGML_OP_DIAG:
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{
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GGML_ASSERT(false); // TODO: not implemented
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} break;
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case GGML_OP_DIAG_MASK_INF:
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{
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// necessary for llama
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@ -12943,20 +13050,30 @@ static void ggml_compute_backward(struct ggml_context * ctx, struct ggml_tensor
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// necessary for llama
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if (src0->grad) {
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// y = softmax(x)
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// dx = dy * y - sum(dy * y) * y
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// dx = y * (dy - sum(dy * y))
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//
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// Jii = yi - yi*yi
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// Jij = -yi*yj
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// J = diag(y)-y.*y
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// dx = J * dy
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// dxk = sum(Jkj * dyk)
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struct ggml_tensor * tensor_t = ggml_cont(ctx,
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ggml_permute(ctx,
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ggml_reshape(ctx,
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tensor,
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ggml_new_tensor(ctx,
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tensor->type,
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4, tensor->ne)),
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1, 0, 2, 3));
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src0->grad =
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ggml_add_impl(ctx,
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src0->grad,
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ggml_mul(ctx,
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tensor,
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ggml_add1(ctx,
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tensor->grad,
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ggml_neg(ctx,
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ggml_sum(ctx,
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ggml_mul(ctx,
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tensor->grad,
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tensor))))),
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ggml_mul_mat(ctx,
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ggml_sub(ctx,
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ggml_diag(ctx, tensor),
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ggml_mul_mat(ctx, tensor_t, tensor_t)),
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tensor->grad),
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inplace);
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}
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} break;
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@ -13480,6 +13597,7 @@ void ggml_graph_compute(struct ggml_context * ctx, struct ggml_cgraph * cgraph)
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case GGML_OP_TRANSPOSE:
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case GGML_OP_GET_ROWS:
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case GGML_OP_GET_ROWS_BACK:
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case GGML_OP_DIAG:
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case GGML_OP_DIAG_MASK_INF:
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{
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node->n_tasks = 1;
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5
ggml.h
5
ggml.h
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@ -285,6 +285,7 @@ extern "C" {
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GGML_OP_TRANSPOSE,
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GGML_OP_GET_ROWS,
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GGML_OP_GET_ROWS_BACK,
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GGML_OP_DIAG,
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GGML_OP_DIAG_MASK_INF,
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GGML_OP_DIAG_MASK_ZERO,
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GGML_OP_SOFT_MAX,
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@ -700,6 +701,10 @@ extern "C" {
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struct ggml_tensor * a,
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struct ggml_tensor * b);
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GGML_API struct ggml_tensor * ggml_diag(
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struct ggml_context * ctx,
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struct ggml_tensor * a);
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// set elements above the diagonal to -INF
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GGML_API struct ggml_tensor * ggml_diag_mask_inf(
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struct ggml_context * ctx,
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