model: add Mellum architecture (#23966)

* model: support for Mellum architecture

* model: improve mellum.py formatting

* model: improve mellum.py formatting once again

* deps: downgrade transformers to 4.57.6 (to fix CI)

* deps: remove huggingface_hub dependency

* deps: remove huggingface_hub from test requirements

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

conversion/__init__.py

@@ -135,6 +135,7 @@ TEXT_MODEL_MAP: dict[str, str] = {
     "Mamba2ForCausalLM": "mamba",
     "MambaForCausalLM": "mamba",
     "MambaLMHeadModel": "mamba",
+    "MellumForCausalLM": "mellum",
     "MiMoV2FlashForCausalLM": "mimo",
     "MiMoV2ForCausalLM": "mimo",
     "MiniCPM3ForCausalLM": "minicpm",

conversion/base.py

@@ -1663,6 +1663,9 @@ class TextModel(ModelBase):
         if chkhsh == "789696f5946cc0fc59371f39f6097cafed196b3acded6140432f26bbb1ae1669":
             # ref: https://huggingface.co/ibm-granite/granite-embedding-311m-multilingual-r2
             res = "granite-embed-multi-311m"
+        if chkhsh == "9dcf830ee9990cdbf78cc523a5f7bd9ad8f3f9890c2d3581d2785ad10f07049d":
+            # ref: https://huggingface.co/JetBrains/Mellum2-12B-A2.5B-Base
+            res = "mellum2"
 
         if res is None:
             logger.warning("\n")

conversion/mellum.py

@@ -0,0 +1,61 @@
+from __future__ import annotations
+
+from typing import Iterable, TYPE_CHECKING
+
+import torch
+
+if TYPE_CHECKING:
+    from torch import Tensor
+
+from .base import ModelBase, TextModel, gguf, logger
+
+
+@ModelBase.register("MellumForCausalLM")
+class MellumModel(TextModel):
+    model_arch = gguf.MODEL_ARCH.MELLUM
+
+    def set_gguf_parameters(self):
+        super().set_gguf_parameters()
+        if (moe_intermediate_size := self.hparams.get("moe_intermediate_size")) is not None:
+            self.gguf_writer.add_expert_feed_forward_length(moe_intermediate_size)
+            logger.info(f"gguf: expert feed forward length = {moe_intermediate_size}")
+
+        use_sliding_window = self.hparams.get("use_sliding_window")
+        sliding_window = self.hparams.get("sliding_window")
+        if (use_sliding_window is True or use_sliding_window is None) and sliding_window is not None:
+            self.gguf_writer.add_sliding_window(sliding_window)
+            logger.info(f"gguf: sliding window = {sliding_window}")
+            self.gguf_writer.add_sliding_window_pattern([t == "sliding_attention" for t in self.hparams["layer_types"]])
+            logger.info(f"gguf: sliding window pattern length = {len(self.hparams['layer_types'])}")
+
+    _experts: list[dict[str, Tensor]] | None = None
+
+    def modify_tensors(self, data_torch: Tensor, name: str, bid: int | None) -> Iterable[tuple[str, Tensor]]:
+        if name.find("experts") != -1:
+            n_experts = self.find_hparam(["num_local_experts", "num_experts"])
+            assert bid is not None
+
+            if self._experts is None:
+                self._experts = [{} for _ in range(self.block_count)]
+
+            self._experts[bid][name] = data_torch
+
+            if len(self._experts[bid]) >= n_experts * 3:
+                for w_name in ["down_proj", "gate_proj", "up_proj"]:
+                    datas: list[Tensor] = []
+
+                    for xid in range(n_experts):
+                        ename = f"model.layers.{bid}.mlp.experts.{xid}.{w_name}.weight"
+                        datas.append(self._experts[bid][ename])
+                        del self._experts[bid][ename]
+
+                    data_torch = torch.stack(datas, dim=0)
+
+                    merged_name = f"model.layers.{bid}.mlp.experts.{w_name}.weight"
+
+                    yield from super().modify_tensors(data_torch, merged_name, bid)
+                return
+            else:
+                return
+
+        yield from super().modify_tensors(data_torch, name, bid)