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1 # SPDX-License-Identifier: Apache-2.0
2 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
3
4 from collections.abc import Iterable
5 from itertools import islice
6
7 import torch
8 from torch import nn
9 from transformers import CohereConfig
10
11 from vllm.compilation.decorators import support_torch_compile
12 from vllm.config import CacheConfig, VllmConfig
13 from vllm.distributed import (
14 get_pp_group,
15 get_tensor_model_parallel_world_size,
16 )
17 from vllm.model_executor.layers.activation import SiluAndMul
18 from vllm.model_executor.layers.attention import Attention
19 from vllm.model_executor.layers.fused_moe import (
20 FusedMoEFactory,
21 GateLinear,
22 )
23 from vllm.model_executor.layers.linear import (
24 MergedColumnParallelLinear,
25 QKVParallelLinear,
26 RowParallelLinear,
27 )
28 from vllm.model_executor.layers.logits_processor import LogitsProcessor
29 from vllm.model_executor.layers.quantization import QuantizationConfig
30 from vllm.model_executor.layers.rotary_embedding import get_rope
31 from vllm.model_executor.layers.vocab_parallel_embedding import VocabParallelEmbedding
32 from vllm.model_executor.model_loader.weight_utils import (
33 row_parallel_weight_loader,
34 )
35 from vllm.model_executor.utils import set_weight_attrs
36 from vllm.platforms import current_platform
37 from vllm.sequence import IntermediateTensors
38
39 from .commandr import LayerNorm
40 from .interfaces import EagleModelMixin, SupportsEagle3, SupportsPP, SupportsQuant
41 from .utils import (
42 AutoWeightsLoader,
43 WeightsMapper,
44 extract_layer_index,
45 make_empty_intermediate_tensors_factory,
46 make_layers,
47 maybe_prefix,
48 )
49
50
51 def is_prefix_dense_layer(config: CohereConfig, layer_idx: int) -> bool:
52 """True when layer_idx lies in the contiguous dense MLP prefix."""
53 if layer_idx >= len(config.mlp_layer_types):
54 return False
55 return all(t == "dense" for t in config.mlp_layer_types[: layer_idx + 1])
56
57
58 @torch.compile(backend=current_platform.simple_compile_backend)
59 def token_choice_with_bias(
60 hidden_states: torch.Tensor,
61 gating_output: torch.Tensor,
62 topk: int,
63 renormalize: bool,
64 ):
65 """Sigmoid -> top-k (-> renormalize) custom routing for Cohere2Moe."""
66 assert hidden_states.shape[0] == gating_output.shape[0], "Number of tokens mismatch"
67
68 scores = gating_output.float().sigmoid()
69 topk_weights, topk_ids = torch.topk(scores, k=topk, dim=-1, sorted=False)
70
71 if renormalize:
72 topk_weights = topk_weights / topk_weights.sum(dim=-1, keepdim=True)
73
74 return topk_weights.to(torch.float32), topk_ids.to(torch.int32)
75
76
77 @torch.compile(backend=current_platform.simple_compile_backend)
78 def rms_norm_func(hidden_states, weight, variance_epsilon):
79 input_dtype = hidden_states.dtype
80 hidden_states = hidden_states.to(torch.float32)
81 variance = hidden_states.pow(2).mean(-1, keepdim=True)
82 hidden_states = hidden_states * torch.rsqrt(variance + variance_epsilon)
83 hidden_states = weight.to(torch.float32) * hidden_states
84 return hidden_states.to(input_dtype)
85
86
87 class RMSNorm(nn.Module):
88 def __init__(self, param_shape=None, eps=1e-6):
89 super().__init__()
90 self.weight = nn.Parameter(torch.ones(param_shape))
91 self.variance_epsilon = eps
92 set_weight_attrs(self.weight, {"weight_loader": row_parallel_weight_loader})
93
94 def forward(self, hidden_states, residuals=None):
95 hidden_states = rms_norm_func(hidden_states, self.weight, self.variance_epsilon)
96 return hidden_states, residuals
97
98
99 def select_norm_impl(config: CohereConfig) -> tuple[type[nn.Module], float]:
100 """Returns (norm_class, eps). Uses RMSNorm when config.rms_norm_eps is set,
101 otherwise falls back to LayerNorm with config.layer_norm_eps."""
102 rms_eps = getattr(config, "rms_norm_eps", None)
103 if rms_eps is not None:
104 return RMSNorm, rms_eps
105 return LayerNorm, config.layer_norm_eps
106
107
108 class Cohere2MoeMLP(nn.Module):
109 """Cohere MLP used as shared experts in the MoE block."""
110
111 def __init__(
112 self,
113 config: CohereConfig,
114 intermediate_size: int | None = None,
115 quant_config: QuantizationConfig | None = None,
116 reduce_results: bool = False,
117 prefix: str = "",
118 ):
119 super().__init__()
120 self.config = config
121 self.hidden_size = config.hidden_size
122 self.intermediate_size = (
123 intermediate_size
124 if intermediate_size is not None
125 else config.intermediate_size
126 )
127 self.gate_up_proj = MergedColumnParallelLinear(
128 self.hidden_size,
129 [self.intermediate_size] * 2,
130 bias=False,
131 quant_config=quant_config,
132 prefix=f"{prefix}.gate_up_proj",
133 )
134 self.down_proj = RowParallelLinear(
135 self.intermediate_size,
136 self.hidden_size,
137 bias=False,
138 quant_config=quant_config,
139 reduce_results=reduce_results,
140 prefix=f"{prefix}.down_proj",
141 )
142 self.act_fn = SiluAndMul()
143
144 def forward(self, x):
145 gate_up, _ = self.gate_up_proj(x)
146 x = self.act_fn(gate_up)
147 x, _ = self.down_proj(x)
148 return x
149
150
151 class Cohere2MoeAttention(nn.Module):
152 """Cohere MoE attention with sliding-window interleave."""
153
154 def __init__(
155 self,
156 config: CohereConfig,
157 cache_config: CacheConfig | None = None,
158 quant_config: QuantizationConfig | None = None,
159 prefix: str = "",
160 ):
161 super().__init__()
162 tp_size = get_tensor_model_parallel_world_size()
163 self.config = config
164 self.layer_idx = extract_layer_index(prefix)
165 self.hidden_size = config.hidden_size
166 self.total_num_heads = config.num_attention_heads
167 self.num_heads = self.total_num_heads // tp_size
168 self.head_dim = getattr(
169 config, "head_dim", self.hidden_size // self.total_num_heads
170 )
171 self.total_num_kv_heads = config.num_key_value_heads
172 if self.total_num_kv_heads >= tp_size:
173 assert self.total_num_kv_heads % tp_size == 0
174 else:
175 assert tp_size % self.total_num_kv_heads == 0
176 self.num_kv_heads = max(1, self.total_num_kv_heads // tp_size)
177 self.q_size = self.num_heads * self.head_dim
178 self.kv_size = self.num_kv_heads * self.head_dim
179 self.scaling = self.head_dim**-0.5
180 self.max_position_embeddings = getattr(
181 config, "model_max_length", None
182 ) or getattr(config, "max_position_embeddings", 8192)
183 assert isinstance(self.max_position_embeddings, int)
184 self.qkv_proj = QKVParallelLinear(
185 self.hidden_size,
186 self.head_dim,
187 self.total_num_heads,
188 self.total_num_kv_heads,
189 bias=False,
190 quant_config=quant_config,
191 prefix=f"{prefix}.qkv_proj",
192 )
193 self.o_proj = RowParallelLinear(
194 self.total_num_heads * self.head_dim,
195 self.hidden_size,
196 bias=False,
197 quant_config=quant_config,
198 prefix=f"{prefix}.o_proj",
199 )
200 self.rotary_emb = get_rope(
201 self.head_dim,
202 max_position=self.max_position_embeddings,
203 rope_parameters=config.rope_parameters,
204 is_neox_style=False,
205 )
206
207 self.sliding_window = None
208 layer_types = getattr(config, "layer_types", None)
209 if (
210 layer_types is not None
211 and layer_types[self.layer_idx] == "sliding_attention"
212 ):
213 self.sliding_window = config.sliding_window + 1
214
215 # Prefix-dense layers have full attention (no sliding window). When
216 # prefix_dense_sliding_window_pattern == 1, they keep RoPE even though
217 # they are not sliding-window layers.
218 prefix_dense_sliding_window_pattern = getattr(
219 config, "prefix_dense_sliding_window_pattern", 1
220 )
221 self.force_rope = bool(
222 is_prefix_dense_layer(config, self.layer_idx)
223 and prefix_dense_sliding_window_pattern == 1
224 )
225
226 self.attn = Attention(
227 self.num_heads,
228 self.head_dim,
229 self.scaling,
230 num_kv_heads=self.num_kv_heads,
231 cache_config=cache_config,
232 quant_config=quant_config,
233 per_layer_sliding_window=self.sliding_window,
234 prefix=f"{prefix}.attn",
235 )
236
237 def forward(
238 self,
239 positions: torch.Tensor,
240 hidden_states: torch.Tensor,
241 ) -> torch.Tensor:
242 qkv, _ = self.qkv_proj(hidden_states)
243 q, k, v = qkv.split([self.q_size, self.kv_size, self.kv_size], dim=-1)
244 if self.sliding_window or self.force_rope:
245 q, k = self.rotary_emb(positions, q, k)
246 attn_output = self.attn(q, k, v)
247 output, _ = self.o_proj(attn_output)
248 return output
249
250
251 class Cohere2Moe(nn.Module):
252 """Tensor-parallel MoE block for Cohere2Moe with shared experts."""
253
254 def __init__(
255 self,
256 config: CohereConfig,
257 params_dtype: torch.dtype | None = None,
258 quant_config: QuantizationConfig | None = None,
259 tp_size: int | None = None,
260 prefix: str = "",
261 ):
262 super().__init__()
263 self.hidden_size = config.hidden_size
264 self.tp_size = get_tensor_model_parallel_world_size()
265
266 if self.tp_size > config.num_experts:
267 raise ValueError(
268 f"Tensor parallel size {self.tp_size} is greater than "
269 f"the number of experts {config.num_experts}."
270 )
271
272 if (
273 hasattr(config, "expert_selection_fn")
274 and config.expert_selection_fn == "sigmoid"
275 ):
276 self.custom_routing_function = token_choice_with_bias
277 else:
278 self.custom_routing_function = None
279
280 self.gate = GateLinear(
281 config.hidden_size,
282 config.num_experts,
283 params_dtype=params_dtype,
284 prefix=f"{prefix}.gate",
285 )
286
287 self.shared_experts: Cohere2MoeMLP | None
288 if hasattr(config, "num_shared_experts") and config.num_shared_experts > 0:
289 self.shared_experts = Cohere2MoeMLP(
290 config=config,
291 intermediate_size=config.intermediate_size * config.num_shared_experts,
292 quant_config=quant_config,
293 prefix=f"{prefix}.shared_experts",
294 )
295 self.shared_expert_combination_strategy = getattr(
296 config, "shared_expert_combination_strategy", "sum"
297 )
298 assert self.shared_expert_combination_strategy in ("average", "sum"), (
299 "shared_expert_combination_strategy must be one of ['average', 'sum']"
300 )
301 else:
302 self.shared_experts = None
303 self.shared_expert_combination_strategy = None
304
305 self.experts = FusedMoEFactory(
306 num_experts=config.num_experts,
307 top_k=config.num_experts_per_tok,
308 hidden_size=config.hidden_size,
309 intermediate_size=config.intermediate_size,
310 params_dtype=params_dtype,
311 renormalize=getattr(config, "norm_topk_prob", True),
312 quant_config=quant_config,
313 tp_size=tp_size,
314 prefix=f"{prefix}.experts",
315 custom_routing_function=self.custom_routing_function,
316 shared_experts=self.shared_experts,
317 )
318
319 def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
320 orig_shape = hidden_states.shape
321 hidden_states = hidden_states.view(-1, self.hidden_size)
322 router_logits, _ = self.gate(hidden_states)
323 # FusedMoEFactory handles shared expert overlap internally and returns
324 # shared_output + routed_output when shared_experts is set.
325 final_hidden_states = self.experts(hidden_states, router_logits)
326 if self.shared_expert_combination_strategy == "average":
327 final_hidden_states = final_hidden_states / 2
328 return final_hidden_states.view(orig_shape)
329
330
331 class Cohere2MoeDecoderLayer(nn.Module):
332 def __init__(
333 self,
334 config: CohereConfig,
335 cache_config: CacheConfig | None = None,
336 quant_config: QuantizationConfig | None = None,
337 prefix: str = "",
338 ):
339 super().__init__()
340 self.config = config
341 self.hidden_size = config.hidden_size
342 self.layer_idx = extract_layer_index(prefix)
343
344 self.self_attn = Cohere2MoeAttention(
345 config,
346 cache_config,
347 quant_config=quant_config,
348 prefix=f"{prefix}.self_attn",
349 )
350
351 if config.mlp_layer_types[self.layer_idx] == "dense":
352 self.mlp = Cohere2MoeMLP(
353 config=config,
354 intermediate_size=getattr(
355 config, "prefix_dense_intermediate_size", config.intermediate_size
356 ),
357 quant_config=quant_config,
358 reduce_results=True,
359 prefix=f"{prefix}.mlp",
360 )
361 else:
362 self.mlp = Cohere2Moe(
363 config=config, quant_config=quant_config, prefix=f"{prefix}.mlp"
364 )
365
366 norm_cls, norm_eps = select_norm_impl(config)
367 self.input_layernorm = norm_cls(param_shape=(config.hidden_size,), eps=norm_eps)
368
369 def forward(
370 self,
371 positions: torch.Tensor,
372 hidden_states: torch.Tensor,
373 residual: torch.Tensor | None,
374 ) -> tuple[torch.Tensor, torch.Tensor]:
375 residual = hidden_states
376 hidden_states, residual = self.input_layernorm(hidden_states, residual)
377 hidden_states_attention = self.self_attn(
378 positions=positions,
379 hidden_states=hidden_states,
380 )
381 hidden_states_mlp = self.mlp(hidden_states)
382
383 hidden_states = residual + hidden_states_attention + hidden_states_mlp
384 return hidden_states, residual
385
386
387 @support_torch_compile
388 class Cohere2MoeModel(nn.Module, EagleModelMixin):
389 """Transformer decoder for Cohere2Moe."""
390
391 def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
392 super().__init__()
393
394 config = vllm_config.model_config.hf_config
395 cache_config = vllm_config.cache_config
396 quant_config = vllm_config.quant_config
397
398 self.config = config
399 self.quant_config = quant_config
400 self.vocab_size = config.vocab_size
401 self.org_vocab_size = config.vocab_size
402 self.embed_tokens = VocabParallelEmbedding(
403 config.vocab_size, config.hidden_size
404 )
405
406 # Decoder layers read per-layer MLP layout from config.mlp_layer_types
407 # (dense MLP vs MoE) and use it for weight loading. Transformers >=5.10
408 # populates this field; older versions only expose first_k_dense_replace.
409 # Normalize here so layer construction below sees a consistent layout.
410 if getattr(config, "mlp_layer_types", None) is None:
411 first_k_dense_replace = getattr(config, "first_k_dense_replace", None)
412 n = config.num_hidden_layers
413 if first_k_dense_replace is not None:
414 config.mlp_layer_types = ["dense"] * first_k_dense_replace + [
415 "sparse"
416 ] * (n - first_k_dense_replace)
417 else:
418 config.mlp_layer_types = ["sparse"] * n
419
420 self.start_layer, self.end_layer, self.layers = make_layers(
421 config.num_hidden_layers,
422 lambda prefix: Cohere2MoeDecoderLayer(
423 config, cache_config, quant_config, prefix=prefix
424 ),
425 prefix=f"{prefix}.layers",
426 )
427 norm_cls, norm_eps = select_norm_impl(config)
428 self.norm = norm_cls(param_shape=(config.hidden_size,), eps=norm_eps)
429 self.make_empty_intermediate_tensors = make_empty_intermediate_tensors_factory(
430 ["hidden_states", "residual"], config.hidden_size
431 )
432
433 def get_input_embeddings(self, input_ids: torch.Tensor) -> torch.Tensor:
434 return self.embed_tokens(input_ids)
435
436 def forward(
437 self,
438 input_ids: torch.Tensor,
439 positions: torch.Tensor,
440 intermediate_tensors: IntermediateTensors | None = None,
441 inputs_embeds: torch.Tensor | None = None,
442 ) -> torch.Tensor | IntermediateTensors | tuple[torch.Tensor, list[torch.Tensor]]:
443 if get_pp_group().is_first_rank:
444 if inputs_embeds is not None:
445 hidden_states = inputs_embeds
446 else:
447 hidden_states = self.get_input_embeddings(input_ids)
448 residual = None
449 else:
450 assert intermediate_tensors is not None
451 hidden_states = intermediate_tensors["hidden_states"]
452 residual = intermediate_tensors["residual"]
453
454 aux_hidden_states = []
455 if self.start_layer in self.aux_hidden_state_layers:
456 aux_hidden_states.append(hidden_states)
457 for layer_idx, layer in enumerate(
458 islice(self.layers, self.start_layer, self.end_layer),
459 start=self.start_layer,
460 ):
461 hidden_states, residual = layer(positions, hidden_states, residual)
462 if layer_idx + 1 in self.aux_hidden_state_layers:
463 aux_hidden_states.append(hidden_states)
464 if not get_pp_group().is_last_rank:
465 return IntermediateTensors(
466 {"hidden_states": hidden_states, "residual": residual}
467 )
468 hidden_states, _ = self.norm(hidden_states, residual)
469 if aux_hidden_states:
470 return hidden_states, aux_hidden_states
471 return hidden_states
472
473
474 class Cohere2MoeForCausalLM(nn.Module, SupportsPP, SupportsQuant, SupportsEagle3):
475 is_text_generation_model = True
476
477 hf_to_vllm_mapper = WeightsMapper(
478 orig_to_new_stacked={
479 # weight_name: (param_name, shard_id)
480 ".q_proj": (".qkv_proj", "q"),
481 ".k_proj": (".qkv_proj", "k"),
482 ".v_proj": (".qkv_proj", "v"),
483 # .experts.gate_up_proj must be handled by MoERunner.load_weights for EP
484 ".mlp.gate_proj": (".mlp.gate_up_proj", 0),
485 ".mlp.up_proj": (".mlp.gate_up_proj", 1),
486 ".shared_experts.gate_proj": (".shared_experts.gate_up_proj", 0),
487 ".shared_experts.up_proj": (".shared_experts.gate_up_proj", 1),
488 },
489 orig_to_new_prefix={"lm_head.": None},
490 )
491 packed_modules_mapping = {
492 "qkv_proj": [
493 "q_proj",
494 "k_proj",
495 "v_proj",
496 ],
497 "gate_up_proj": [
498 "gate_proj",
499 "up_proj",
500 ],
501 }
502
503 def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
504 super().__init__()
505 config = vllm_config.model_config.hf_config
506 quant_config = vllm_config.quant_config
507 self.config = config
508 self.unpadded_vocab_size = config.vocab_size
509 self.quant_config = quant_config
510 self.logits_scale = config.logit_scale
511 self.logits_processor = LogitsProcessor(
512 self.unpadded_vocab_size, config.vocab_size, scale=self.logits_scale
513 )
514 self.model = Cohere2MoeModel(
515 vllm_config=vllm_config, prefix=maybe_prefix(prefix, "model")
516 )
517 self.make_empty_intermediate_tensors = (
518 self.model.make_empty_intermediate_tensors
519 )
520
521 def embed_input_ids(self, input_ids: torch.Tensor) -> torch.Tensor:
522 return self.model.get_input_embeddings(input_ids)
523
524 def get_input_embeddings(self, input_ids: torch.Tensor) -> torch.Tensor:
525 return self.model.get_input_embeddings(input_ids)
526
527 @torch.no_grad()
528 def forward(
529 self,
530 input_ids: torch.Tensor,
531 positions: torch.Tensor,
532 intermediate_tensors: IntermediateTensors | None = None,
533 inputs_embeds: torch.Tensor | None = None,
534 ) -> torch.Tensor | IntermediateTensors | tuple[torch.Tensor, list[torch.Tensor]]:
535 return self.model(input_ids, positions, intermediate_tensors, inputs_embeds)
536
537 def compute_logits(
538 self,
539 hidden_states: torch.Tensor,
540 ) -> torch.Tensor | None:
541 return self.logits_processor(self.model.embed_tokens, hidden_states)
542
543 def load_weights(self, weights: Iterable[tuple[str, torch.Tensor]]) -> set[str]:
544 loader = AutoWeightsLoader(self)
545 return loader.load_weights(weights, mapper=self.hf_to_vllm_mapper)