GLM-5 · Causal mask · OpenModelAtlas

Causal mask

tensorcausal_mask_mapping["indexed_attention"]

Position-derived mask supplied to every block.

shape: $M$ [T queries, T keys]

Sources

Contextual evidence from Construct causal mask

The model embeds tokens, numbers positions from the cached length, always builds the causal mask (the indexer needs it), applies the 78 blocks, normalizes and projects to vocabulary logits with an untied lm_head without upcasting them. The checkpoint’s layer 78, the multi-token-prediction layer, is ignored on load.

transformer · huggingface/transformers / modeling_glm_moe_dsa.py
Pinned revision 5e4d6304de55 ↗ · lines 648–802

Read code excerpt

    _keys_to_ignore_on_load_unexpected = [r"model\.layers\.78.*"]

… lines 649–695 omitted …

        if inputs_embeds is None:
            inputs_embeds: torch.Tensor = self.embed_tokens(input_ids)

        if use_cache and past_key_values is None:
            past_key_values = DynamicCache(config=self.config)

        if position_ids is None:
            past_seen_tokens = past_key_values.get_seq_length() if past_key_values is not None else 0
            position_ids = torch.arange(inputs_embeds.shape[1], device=inputs_embeds.device) + past_seen_tokens
            position_ids = position_ids.unsqueeze(0)

        # It may already have been prepared by e.g. `generate`
        if not isinstance(causal_mask_mapping := attention_mask, dict):
            mask_kwargs = {
                "config": self.config,
                "inputs_embeds": inputs_embeds,
                "attention_mask": attention_mask,
                "past_key_values": past_key_values,
                "position_ids": position_ids,
                "allow_is_causal_skip": False,  # Always force creation to account for causality in the indexer
            }
            causal_mask_mapping = {"indexed_attention": create_causal_mask(**mask_kwargs)}

        hidden_states = inputs_embeds
        position_embeddings = self.rotary_emb(hidden_states, position_ids=position_ids)

        topk_indices = None  # MAIN DIFF with DSV3.2
        for i, decoder_layer in enumerate(self.layers[: self.config.num_hidden_layers]):
            hidden_states, topk_indices = decoder_layer(
                hidden_states,
                attention_mask=causal_mask_mapping["indexed_attention"],
                position_embeddings=position_embeddings,
                position_ids=position_ids,
                past_key_values=past_key_values,
                use_cache=use_cache,
                prev_topk_indices=topk_indices,  # MAIN DIFF with DSV3.2
                **kwargs,
            )

        hidden_states = self.norm(hidden_states)
        return BaseModelOutputWithPast(
            last_hidden_state=hidden_states,
            past_key_values=past_key_values,
        )

… lines 740–748 omitted …

    def __init__(self, config):
        super().__init__(config)
        self.model = GlmMoeDsaModel(config)
        self.vocab_size = config.vocab_size
        self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)

… lines 754–798 omitted …

        hidden_states = outputs.last_hidden_state
        # Only compute necessary logits, and do not upcast them to float if we are not computing the loss
        slice_indices = slice(-logits_to_keep, None) if isinstance(logits_to_keep, int) else logits_to_keep
        logits = self.lm_head(hidden_states[:, slice_indices, :])

Contextual evidence from Transformer blocks

A block applies input RMSNorm, attention and a residual addition, then post-attention RMSNorm, the feed-forward network and a second residual addition; the first first_k_dense_replace blocks use the dense MLP, the rest MoE.

block · huggingface/transformers / modeling_glm_moe_dsa.py
Pinned revision 5e4d6304de55 ↗ · lines 586–627

Read code excerpt

class GlmMoeDsaDecoderLayer(GradientCheckpointingLayer):
    def __init__(self, config: GlmMoeDsaConfig, layer_idx: int):
        super().__init__()
        self.hidden_size = config.hidden_size
        self.self_attn = GlmMoeDsaAttention(config, layer_idx)

        self.mlp = GlmMoeDsaMoE(config) if config.mlp_layer_types[layer_idx] == "sparse" else GlmMoeDsaMLP(config)

        self.input_layernorm = GlmMoeDsaRMSNorm(config.hidden_size, config.rms_norm_eps)
        self.post_attention_layernorm = GlmMoeDsaRMSNorm(config.hidden_size, config.rms_norm_eps)

    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        use_cache: bool | None = False,
        position_embeddings: tuple[torch.Tensor, torch.Tensor] | None = None,
        prev_topk_indices: torch.Tensor | None = None,  # MAIN DIFF with DSV3.2
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple[torch.Tensor, torch.Tensor | None]:
        residual = hidden_states
        hidden_states = self.input_layernorm(hidden_states)
        # Self Attention
        hidden_states, _, topk_indices = self.self_attn(
            hidden_states=hidden_states,
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_values=past_key_values,
            use_cache=use_cache,
            position_embeddings=position_embeddings,
            prev_topk_indices=prev_topk_indices,  # MAIN DIFF with DSV3.2
            **kwargs,
        )
        hidden_states = residual + hidden_states

        residual = hidden_states
        hidden_states = self.post_attention_layernorm(hidden_states)
        hidden_states = self.mlp(hidden_states)
        hidden_states = residual + hidden_states
        return hidden_states, topk_indices