[WIP][Flax] Add general conversion script (#10809)

* save intermediate

* finish first version

* delete some more

* improve import

* fix roberta

* Update src/transformers/modeling_flax_pytorch_utils.py
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* Update src/transformers/modeling_flax_pytorch_utils.py
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

* small corrections

* apply all comments

* fix deterministic

* make fix-copies
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

src/transformers/modeling_flax_pytorch_utils.py

+# coding=utf-8
+# Copyright 2021 The HuggingFace Inc. team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+""" PyTorch - TF 2.0 general utilities."""
+
+
+import os
+
+from flax.core.frozen_dict import unfreeze
+from flax.traverse_util import flatten_dict, unflatten_dict
+
+from .utils import logging
+
+
+logger = logging.get_logger(__name__)
+
+
+#####################
+# PyTorch => Flax #
+#####################
+
+
+def load_pytorch_checkpoint_in_flax_state_dict(flax_model, pytorch_checkpoint_path, allow_missing_keys=False):
+    """Load pytorch checkpoints in a flax model"""
+    try:
+        import torch  # noqa: F401
+    except ImportError:
+        logger.error(
+            "Loading a PyTorch model in Flax, requires both PyTorch and  Flax to be installed. Please see "
+            "https://pytorch.org/ and https://flax.readthedocs.io/en/latest/installation.html for installation instructions."
+        )
+        raise
+
+    pt_path = os.path.abspath(pytorch_checkpoint_path)
+    logger.info("Loading PyTorch weights from {}".format(pt_path))
+
+    pt_state_dict = torch.load(pt_path, map_location="cpu")
+    logger.info("PyTorch checkpoint contains {sum(t.numel() for t in pt_state_dict.values())} parameters.")
+
+    flax_state_dict = convert_pytorch_state_dict_to_flax(pt_state_dict, flax_model)
+
+    return flax_state_dict
+
+
+def convert_pytorch_state_dict_to_flax(pt_state_dict, flax_model):
+    # convert pytorch tensor to numpy
+    pt_state_dict = {k: v.numpy() for k, v in pt_state_dict.items()}
+
+    random_flax_state_dict = flatten_dict(unfreeze(flax_model.params))
+    flax_state_dict = {}
+
+    remove_base_model_prefix = (flax_model.base_model_prefix not in flax_model.params) and (
+        flax_model.base_model_prefix in set([k.split(".")[0] for k in pt_state_dict.keys()])
+    )
+    add_base_model_prefix = (flax_model.base_model_prefix in flax_model.params) and (
+        flax_model.base_model_prefix not in set([k.split(".")[0] for k in pt_state_dict.keys()])
+    )
+
+    # Need to change some parameters name to match Flax names so that we don't have to fork any layer
+    for pt_key, pt_tensor in pt_state_dict.items():
+
+        pt_tuple_key = tuple(pt_key.split("."))
+
+        has_base_model_prefix = pt_tuple_key[0] == flax_model.base_model_prefix
+        require_base_model_prefix = (flax_model.base_model_prefix,) + pt_tuple_key in random_flax_state_dict
+
+        if remove_base_model_prefix and has_base_model_prefix:
+            pt_tuple_key = pt_tuple_key[1:]
+        elif add_base_model_prefix and require_base_model_prefix:
+            pt_tuple_key = (flax_model.base_model_prefix,) + pt_tuple_key
+
+        if pt_tuple_key[-1] == "weight" and pt_tuple_key not in random_flax_state_dict:
+            pt_tuple_key = pt_tuple_key[:-1] + ("kernel",)
+            pt_tensor = pt_tensor.T
+        elif pt_tuple_key[-1] == "gamma":
+            pt_tuple_key = pt_tuple_key[:-1] + ("weight",)
+        elif pt_tuple_key[-1] == "beta":
+            pt_tuple_key = pt_tuple_key[:-1] + ("bias",)
+
+        if pt_tuple_key in random_flax_state_dict:
+            if random_flax_state_dict[pt_tuple_key].shape != pt_tensor.shape:
+                raise ValueError(
+                    "PyTorch checkpoint seems to be incorrect. Weight {pt_key} was expected to be of shape {random_flax_state_dict[pt_tuple_key].shape}, but is {pt_tensor.shape}."
+                )
+
+        # add unexpected weight so that warning is thrown
+        flax_state_dict[pt_tuple_key] = pt_tensor
+
+    return unflatten_dict(flax_state_dict)

src/transformers/modeling_flax_utils.py

@@ -14,7 +14,7 @@
 # limitations under the License.
 
 import os
-from abc import ABC, abstractmethod
+from abc import ABC
 from functools import partial
 from pickle import UnpicklingError
 from typing import Dict, Set, Tuple, Union
@@ -29,6 +29,7 @@ from jax.random import PRNGKey
 
 from .configuration_utils import PretrainedConfig
 from .file_utils import FLAX_WEIGHTS_NAME, WEIGHTS_NAME, cached_path, hf_bucket_url, is_offline_mode, is_remote_url
+from .modeling_flax_pytorch_utils import load_pytorch_checkpoint_in_flax_state_dict
 from .utils import logging
 
 
@@ -121,11 +122,6 @@ class FlaxPreTrainedModel(ABC):
             )
         self._params = freeze(params)
 
-    @staticmethod
-    @abstractmethod
-    def convert_from_pytorch(pt_state: Dict, config: PretrainedConfig) -> Dict:
-        raise NotImplementedError()
-
     @classmethod
     def from_pretrained(
         cls,
@@ -307,24 +303,17 @@ class FlaxPreTrainedModel(ABC):
         else:
             resolved_archive_file = None
 
-        # Instantiate model.
-        with open(resolved_archive_file, "rb") as state_f:
-            try:
-                if from_pt:
-                    import torch
-
-                    state = torch.load(state_f)
+        # init random models
+        model = cls(config, *model_args, **model_kwargs)
 
-                    state = convert_state_dict_from_pt(cls, state, config)
+        if from_pt:
+            state = load_pytorch_checkpoint_in_flax_state_dict(model, resolved_archive_file)
         else:
+            with open(resolved_archive_file, "rb") as state_f:
+                try:
                     state = from_bytes(cls, state_f.read())
                 except UnpicklingError:
-                raise EnvironmentError(
-                    f"Unable to convert pytorch model {archive_file} to Flax deserializable object. "
-                )
-
-        # init random models
-        model = cls(config, *model_args, **model_kwargs)
+                    raise EnvironmentError(f"Unable to convert {archive_file} to Flax deserializable object. ")
 
         # if model is base model only use model_prefix key
         if cls.base_model_prefix not in dict(model.params) and cls.base_model_prefix in state:
@@ -341,6 +330,10 @@ class FlaxPreTrainedModel(ABC):
         for missing_key in missing_keys:
             state[missing_key] = random_state[missing_key]
 
+        # remove unexpected keys to not be saved again
+        for unexpected_key in unexpected_keys:
+            del state[unexpected_key]
+
         if len(unexpected_keys) > 0:
             logger.warning(
                 f"Some weights of the model checkpoint at {pretrained_model_name_or_path} were not used when "
@@ -393,13 +386,3 @@ class FlaxPreTrainedModel(ABC):
         with open(os.path.join(save_directory, FLAX_WEIGHTS_NAME), "wb") as f:
             model_bytes = to_bytes(self.params)
             f.write(model_bytes)
-
-
-def convert_state_dict_from_pt(model_class: ABC, state: Dict, config: PretrainedConfig):
-    """
-    Converts a PyTorch parameter state dict to an equivalent Flax parameter state dict
-    """
-    state = {k: v.numpy() for k, v in state.items()}
-    state = model_class.convert_from_pytorch(state, config)
-    state = unflatten_dict({tuple(k.split(".")): v for k, v in state.items()})
-    return state

src/transformers/models/bert/modeling_flax_bert.py

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import Callable, Dict, Tuple
+from typing import Callable, Tuple
 
 import numpy as np
 
@@ -21,6 +21,8 @@ import flax.linen as nn
 import jax
 import jax.numpy as jnp
 from flax.core.frozen_dict import FrozenDict
+from flax.linen import dot_product_attention
+from jax import lax
 from jax.random import PRNGKey
 
 from ...file_utils import add_start_docstrings, add_start_docstrings_to_model_forward
@@ -99,17 +101,15 @@ class FlaxBertLayerNorm(nn.Module):
 
     hidden_size: int
     epsilon: float = 1e-6
-    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
-    bias: bool = True  # If True, bias (beta) is added.
-    scale: bool = True  # If True, multiply by scale (gamma). When the next layer is linear
-    # (also e.g. nn.relu), this can be disabled since the scaling will be
-    # done by the next layer.
+    dtype: jnp.dtype = jnp.float32
+    use_bias: bool = True
+    scale: bool = True
     scale_init: Callable[..., np.ndarray] = jax.nn.initializers.ones
     bias_init: Callable[..., np.ndarray] = jax.nn.initializers.zeros
 
     def setup(self):
-        self.gamma = self.param("gamma", self.scale_init, (self.hidden_size,))
-        self.beta = self.param("beta", self.scale_init, (self.hidden_size,))
+        self.weight = self.param("weight", self.scale_init, (self.hidden_size,))
+        self.bias = self.param("bias", self.scale_init, (self.hidden_size,))
 
     def __call__(self, x):
         """
@@ -129,11 +129,11 @@ class FlaxBertLayerNorm(nn.Module):
         mul = jax.lax.rsqrt(var + self.epsilon)
 
         if self.scale:
-            mul = mul * jnp.asarray(self.gamma)
+            mul = mul * jnp.asarray(self.weight)
         y = (x - mean) * mul
 
-        if self.bias:
-            y = y + jnp.asarray(self.beta)
+        if self.use_bias:
+            y = y + jnp.asarray(self.bias)
         return y
 
 
@@ -167,24 +167,21 @@ class FlaxBertEmbeddings(nn.Module):
             self.config.vocab_size,
             self.config.hidden_size,
             initializer_range=self.config.initializer_range,
-            name="word_embeddings",
             dtype=self.dtype,
         )
         self.position_embeddings = FlaxBertEmbedding(
             self.config.max_position_embeddings,
             self.config.hidden_size,
             initializer_range=self.config.initializer_range,
-            name="position_embeddings",
             dtype=self.dtype,
         )
         self.token_type_embeddings = FlaxBertEmbedding(
             self.config.type_vocab_size,
             self.config.hidden_size,
             initializer_range=self.config.initializer_range,
-            name="token_type_embeddings",
             dtype=self.dtype,
         )
-        self.layer_norm = FlaxBertLayerNorm(hidden_size=self.config.hidden_size, name="layer_norm", dtype=self.dtype)
+        self.LayerNorm = FlaxBertLayerNorm(hidden_size=self.config.hidden_size, dtype=self.dtype)
         self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
 
     def __call__(self, input_ids, token_type_ids, position_ids, attention_mask, deterministic: bool = True):
@@ -197,35 +194,116 @@ class FlaxBertEmbeddings(nn.Module):
         hidden_states = inputs_embeds + jnp.broadcast_to(position_embeds, inputs_embeds.shape) + token_type_embeddings
 
         # Layer Norm
-        hidden_states = self.layer_norm(hidden_states)
+        hidden_states = self.LayerNorm(hidden_states)
         hidden_states = self.dropout(hidden_states, deterministic=deterministic)
         return hidden_states
 
 
-class FlaxBertAttention(nn.Module):
+class FlaxBertSelfAttention(nn.Module):
     config: BertConfig
     dtype: jnp.dtype = jnp.float32  # the dtype of the computation
 
     def setup(self):
-        self.self_attention = nn.attention.SelfAttention(
-            num_heads=self.config.num_attention_heads,
-            qkv_features=self.config.hidden_size,
+        if self.config.hidden_size % self.config.num_attention_heads != 0:
+            raise ValueError(
+                "`config.hidden_size`: {self.config.hidden_size} has to be a multiple of `config.num_attention_heads`: {self.config.num_attention_heads}"
+            )
+
+        self.query = nn.Dense(
+            self.config.hidden_size,
+            dtype=self.dtype,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
+        )
+        self.key = nn.Dense(
+            self.config.hidden_size,
+            dtype=self.dtype,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
+        )
+        self.value = nn.Dense(
+            self.config.hidden_size,
+            dtype=self.dtype,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
+        )
+
+    def __call__(self, hidden_states, attention_mask, deterministic=True):
+        head_dim = self.config.hidden_size // self.config.num_attention_heads
+
+        query_states = self.query(hidden_states).reshape(
+            hidden_states.shape[:2] + (self.config.num_attention_heads, head_dim)
+        )
+        value_states = self.value(hidden_states).reshape(
+            hidden_states.shape[:2] + (self.config.num_attention_heads, head_dim)
+        )
+        key_states = self.key(hidden_states).reshape(
+            hidden_states.shape[:2] + (self.config.num_attention_heads, head_dim)
+        )
+
+        # Convert the boolean attention mask to an attention bias.
+        if attention_mask is not None:
+            # attention mask in the form of attention bias
+            attention_mask = jnp.expand_dims(attention_mask, axis=(-3, -2))
+            attention_bias = lax.select(
+                attention_mask > 0,
+                jnp.full(attention_mask.shape, 0.0).astype(self.dtype),
+                jnp.full(attention_mask.shape, -1e10).astype(self.dtype),
+            )
+        else:
+            attention_bias = None
+
+        dropout_rng = None
+        if not deterministic and self.dropout_rate > 0.0:
+            dropout_rng = self.make_rng("dropout")
+
+        attn_output = dot_product_attention(
+            query_states,
+            key_states,
+            value_states,
+            bias=attention_bias,
+            dropout_rng=dropout_rng,
             dropout_rate=self.config.attention_probs_dropout_prob,
+            broadcast_dropout=True,
+            deterministic=deterministic,
+            dtype=self.dtype,
+            precision=None,
+        )
+
+        return attn_output.reshape(attn_output.shape[:2] + (-1,))
+
+
+class FlaxBertSelfOutput(nn.Module):
+    config: BertConfig
+    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
+
+    def setup(self):
+        self.dense = nn.Dense(
+            self.config.hidden_size,
             kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
-            bias_init=jax.nn.initializers.zeros,
-            name="self",
             dtype=self.dtype,
         )
-        self.layer_norm = FlaxBertLayerNorm(hidden_size=self.config.hidden_size, name="layer_norm", dtype=self.dtype)
+        self.LayerNorm = FlaxBertLayerNorm(hidden_size=self.config.hidden_size)
+        self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
+
+    def __call__(self, hidden_states, input_tensor, deterministic: bool = True):
+        hidden_states = self.dense(hidden_states)
+        hidden_states = self.dropout(hidden_states, deterministic=deterministic)
+        hidden_states = self.LayerNorm(hidden_states + input_tensor)
+        return hidden_states
+
+
+class FlaxBertAttention(nn.Module):
+    config: BertConfig
+    dtype: jnp.dtype = jnp.float32
+
+    def setup(self):
+        self.self = FlaxBertSelfAttention(self.config, dtype=self.dtype)
+        self.output = FlaxBertSelfOutput(self.config, dtype=self.dtype)
 
     def __call__(self, hidden_states, attention_mask, deterministic=True):
         # Attention mask comes in as attention_mask.shape == (*batch_sizes, kv_length)
         # FLAX expects: attention_mask.shape == (*batch_sizes, 1, 1, kv_length) such that it is broadcastable
         # with attn_weights.shape == (*batch_sizes, num_heads, q_length, kv_length)
-        attention_mask = jnp.expand_dims(attention_mask, axis=(-3, -2))
-        self_attn_output = self.self_attention(hidden_states, attention_mask, deterministic=deterministic)
-
-        hidden_states = self.layer_norm(self_attn_output + hidden_states)
+        attn_output = self.self(hidden_states, attention_mask, deterministic=deterministic)
+        hidden_states = self.output(attn_output, hidden_states, deterministic=deterministic)
         return hidden_states
 
 
@@ -237,7 +315,6 @@ class FlaxBertIntermediate(nn.Module):
         self.dense = nn.Dense(
             self.config.intermediate_size,
             kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
-            name="dense",
             dtype=self.dtype,
         )
         self.activation = ACT2FN[self.config.hidden_act]
@@ -256,16 +333,15 @@ class FlaxBertOutput(nn.Module):
         self.dense = nn.Dense(
             self.config.hidden_size,
             kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
-            name="dense",
             dtype=self.dtype,
         )
         self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
-        self.layer_norm = FlaxBertLayerNorm(hidden_size=self.config.hidden_size, name="layer_norm", dtype=self.dtype)
+        self.LayerNorm = FlaxBertLayerNorm(hidden_size=self.config.hidden_size, dtype=self.dtype)
 
     def __call__(self, hidden_states, attention_output, deterministic: bool = True):
         hidden_states = self.dense(hidden_states)
         hidden_states = self.dropout(hidden_states, deterministic=deterministic)
-        hidden_states = self.layer_norm(hidden_states + attention_output)
+        hidden_states = self.LayerNorm(hidden_states + attention_output)
         return hidden_states
 
 
@@ -274,9 +350,9 @@ class FlaxBertLayer(nn.Module):
     dtype: jnp.dtype = jnp.float32  # the dtype of the computation
 
     def setup(self):
-        self.attention = FlaxBertAttention(self.config, name="attention", dtype=self.dtype)
-        self.intermediate = FlaxBertIntermediate(self.config, name="intermediate", dtype=self.dtype)
-        self.output = FlaxBertOutput(self.config, name="output", dtype=self.dtype)
+        self.attention = FlaxBertAttention(self.config, dtype=self.dtype)
+        self.intermediate = FlaxBertIntermediate(self.config, dtype=self.dtype)
+        self.output = FlaxBertOutput(self.config, dtype=self.dtype)
 
     def __call__(self, hidden_states, attention_mask, deterministic: bool = True):
         attention_output = self.attention(hidden_states, attention_mask, deterministic=deterministic)
@@ -305,10 +381,10 @@ class FlaxBertEncoder(nn.Module):
     dtype: jnp.dtype = jnp.float32  # the dtype of the computation
 
     def setup(self):
-        self.layers = FlaxBertLayerCollection(self.config, name="layer", dtype=self.dtype)
+        self.layer = FlaxBertLayerCollection(self.config, dtype=self.dtype)
 
     def __call__(self, hidden_states, attention_mask, deterministic: bool = True):
-        return self.layers(hidden_states, attention_mask, deterministic=deterministic)
+        return self.layer(hidden_states, attention_mask, deterministic=deterministic)
 
 
 class FlaxBertPooler(nn.Module):
@@ -319,7 +395,6 @@ class FlaxBertPooler(nn.Module):
         self.dense = nn.Dense(
             self.config.hidden_size,
             kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
-            name="dense",
             dtype=self.dtype,
         )
 
@@ -334,14 +409,14 @@ class FlaxBertPredictionHeadTransform(nn.Module):
     dtype: jnp.dtype = jnp.float32
 
     def setup(self):
-        self.dense = nn.Dense(self.config.hidden_size, name="dense", dtype=self.dtype)
+        self.dense = nn.Dense(self.config.hidden_size, dtype=self.dtype)
         self.activation = ACT2FN[self.config.hidden_act]
-        self.layer_norm = FlaxBertLayerNorm(hidden_size=self.config.hidden_size, name="layer_norm", dtype=self.dtype)
+        self.LayerNorm = FlaxBertLayerNorm(hidden_size=self.config.hidden_size, dtype=self.dtype)
 
     def __call__(self, hidden_states):
         hidden_states = self.dense(hidden_states)
         hidden_states = self.activation(hidden_states)
-        return self.layer_norm(hidden_states)
+        return self.LayerNorm(hidden_states)
 
 
 class FlaxBertLMPredictionHead(nn.Module):
@@ -349,14 +424,10 @@ class FlaxBertLMPredictionHead(nn.Module):
     dtype: jnp.dtype = jnp.float32
 
     def setup(self):
-        self.transform = FlaxBertPredictionHeadTransform(self.config, name="transform", dtype=self.dtype)
-        self.decoder = nn.Dense(self.config.vocab_size, name="decoder", dtype=self.dtype)
+        self.transform = FlaxBertPredictionHeadTransform(self.config, dtype=self.dtype)
+        self.decoder = nn.Dense(self.config.vocab_size, dtype=self.dtype)
 
     def __call__(self, hidden_states):
-        # TODO: The output weights are the same as the input embeddings, but there is
-        #   an output-only bias for each token.
-        #   Need a link between the two variables so that the bias is correctly
-        #   resized with `resize_token_embeddings`
         hidden_states = self.transform(hidden_states)
         hidden_states = self.decoder(hidden_states)
         return hidden_states
@@ -367,10 +438,10 @@ class FlaxBertOnlyMLMHead(nn.Module):
     dtype: jnp.dtype = jnp.float32
 
     def setup(self):
-        self.mlm_head = FlaxBertLMPredictionHead(self.config, name="predictions", dtype=self.dtype)
+        self.predictions = FlaxBertLMPredictionHead(self.config, dtype=self.dtype)
 
     def __call__(self, hidden_states):
-        hidden_states = self.mlm_head(hidden_states)
+        hidden_states = self.predictions(hidden_states)
         return hidden_states
 
 
@@ -405,85 +476,6 @@ class FlaxBertPreTrainedModel(FlaxPreTrainedModel):
 
         return self.module.init(rngs, input_ids, attention_mask, token_type_ids, position_ids)["params"]
 
-    @staticmethod
-    def convert_from_pytorch(pt_state: Dict, config: BertConfig) -> Dict:
-        jax_state = dict(pt_state)
-
-        # Need to change some parameters name to match Flax names so that we don't have to fork any layer
-        for key, tensor in pt_state.items():
-            # Key parts
-            key_parts = set(key.split("."))
-
-            # Every dense layer has "kernel" parameters instead of "weight"
-            if "dense.weight" in key:
-                del jax_state[key]
-                key = key.replace("weight", "kernel")
-                jax_state[key] = tensor
-
-            if "decoder.weight" in key:
-                del jax_state[key]
-                key = key.replace("weight", "kernel")
-                jax_state[key] = tensor.T
-
-            # SelfAttention needs also to replace "weight" by "kernel"
-            if {"query", "key", "value"} & key_parts:
-
-                # Flax SelfAttention decomposes the heads (num_head, size // num_heads)
-                if "bias" in key:
-                    jax_state[key] = tensor.reshape((config.num_attention_heads, -1))
-                elif "weight":
-                    del jax_state[key]
-                    key = key.replace("weight", "kernel")
-                    tensor = tensor.reshape((config.num_attention_heads, -1, config.hidden_size)).transpose((2, 0, 1))
-                    jax_state[key] = tensor
-
-            # SelfAttention output is not a separate layer, remove one nesting
-            if "attention.output.dense" in key:
-                del jax_state[key]
-                key = key.replace("attention.output.dense", "attention.self.out")
-                jax_state[key] = tensor
-
-            # SelfAttention output is not a separate layer, remove nesting on layer norm
-            if "attention.output.LayerNorm" in key:
-                del jax_state[key]
-                key = key.replace("attention.output.LayerNorm", "attention.LayerNorm")
-                jax_state[key] = tensor
-
-            # There are some transposed parameters w.r.t their PyTorch counterpart
-            if "intermediate.dense.kernel" in key or "output.dense.kernel" in key or "transform.dense.kernel" in key:
-                jax_state[key] = tensor.T
-
-            # Self Attention output projection needs to be transposed
-            if "out.kernel" in key:
-                jax_state[key] = tensor.reshape((config.hidden_size, config.num_attention_heads, -1)).transpose(
-                    1, 2, 0
-                )
-
-            # Pooler needs to transpose its kernel
-            if "pooler.dense.kernel" in key:
-                jax_state[key] = tensor.T
-
-            # Hack to correctly load some pytorch models
-            if "predictions.bias" in key:
-                del jax_state[key]
-                jax_state[".".join(key.split(".")[:2]) + ".decoder.bias"] = tensor
-
-            # Handle LayerNorm conversion
-            if "LayerNorm" in key:
-                del jax_state[key]
-
-                # Replace LayerNorm by layer_norm
-                new_key = key.replace("LayerNorm", "layer_norm")
-
-                if "weight" in key:
-                    new_key = new_key.replace("weight", "gamma")
-                elif "bias" in key:
-                    new_key = new_key.replace("bias", "beta")
-
-                jax_state[new_key] = tensor
-
-        return jax_state
-
 
 @add_start_docstrings(
     "The bare Bert Model transformer outputting raw hidden-states without any specific head on top.",
@@ -541,9 +533,9 @@ class FlaxBertModule(nn.Module):
     add_pooling_layer: bool = True
 
     def setup(self):
-        self.embeddings = FlaxBertEmbeddings(self.config, name="embeddings", dtype=self.dtype)
-        self.encoder = FlaxBertEncoder(self.config, name="encoder", dtype=self.dtype)
-        self.pooler = FlaxBertPooler(self.config, name="pooler", dtype=self.dtype)
+        self.embeddings = FlaxBertEmbeddings(self.config, dtype=self.dtype)
+        self.encoder = FlaxBertEncoder(self.config, dtype=self.dtype)
+        self.pooler = FlaxBertPooler(self.config, dtype=self.dtype)
 
     def __call__(self, input_ids, attention_mask, token_type_ids, position_ids, deterministic: bool = True):
 
@@ -602,15 +594,13 @@ class FlaxBertForMaskedLMModule(nn.Module):
     dtype: jnp.dtype = jnp.float32
 
     def setup(self):
-        self.encoder = FlaxBertModule(
+        self.bert = FlaxBertModule(
             config=self.config,
             add_pooling_layer=False,
-            name="bert",
         )
         self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
-        self.mlm_head = FlaxBertOnlyMLMHead(
+        self.cls = FlaxBertOnlyMLMHead(
             config=self.config,
-            name="cls",
             dtype=self.dtype,
         )
 
@@ -618,12 +608,10 @@ class FlaxBertForMaskedLMModule(nn.Module):
         self, input_ids, attention_mask=None, token_type_ids=None, position_ids=None, deterministic: bool = True
     ):
         # Model
-        hidden_states = self.encoder(
-            input_ids, attention_mask, token_type_ids, position_ids, deterministic=deterministic
-        )
+        hidden_states = self.bert(input_ids, attention_mask, token_type_ids, position_ids, deterministic=deterministic)
 
         # Compute the prediction scores
         hidden_states = self.dropout(hidden_states, deterministic=deterministic)
-        logits = self.mlm_head(hidden_states)
+        logits = self.cls(hidden_states)
 
         return (logits,)

src/transformers/models/roberta/modeling_flax_roberta.py

@@ -12,7 +12,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from typing import Callable, Dict, Tuple
+from typing import Callable, Tuple
 
 import numpy as np
 
@@ -20,6 +20,8 @@ import flax.linen as nn
 import jax
 import jax.numpy as jnp
 from flax.core.frozen_dict import FrozenDict
+from flax.linen import dot_product_attention
+from jax import lax
 from jax.random import PRNGKey
 
 from ...file_utils import add_start_docstrings, add_start_docstrings_to_model_forward
@@ -116,17 +118,15 @@ class FlaxRobertaLayerNorm(nn.Module):
 
     hidden_size: int
     epsilon: float = 1e-6
-    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
-    bias: bool = True  # If True, bias (beta) is added.
-    scale: bool = True  # If True, multiply by scale (gamma). When the next layer is linear
-    # (also e.g. nn.relu), this can be disabled since the scaling will be
-    # done by the next layer.
+    dtype: jnp.dtype = jnp.float32
+    use_bias: bool = True
+    scale: bool = True
     scale_init: Callable[..., np.ndarray] = jax.nn.initializers.ones
     bias_init: Callable[..., np.ndarray] = jax.nn.initializers.zeros
 
     def setup(self):
-        self.gamma = self.param("gamma", self.scale_init, (self.hidden_size,))
-        self.beta = self.param("beta", self.scale_init, (self.hidden_size,))
+        self.weight = self.param("weight", self.scale_init, (self.hidden_size,))
+        self.bias = self.param("bias", self.scale_init, (self.hidden_size,))
 
     def __call__(self, x):
         """
@@ -146,11 +146,11 @@ class FlaxRobertaLayerNorm(nn.Module):
         mul = jax.lax.rsqrt(var + self.epsilon)
 
         if self.scale:
-            mul = mul * jnp.asarray(self.gamma)
+            mul = mul * jnp.asarray(self.weight)
         y = (x - mean) * mul
 
-        if self.bias:
-            y = y + jnp.asarray(self.beta)
+        if self.use_bias:
+            y = y + jnp.asarray(self.bias)
         return y
 
 
@@ -186,26 +186,21 @@ class FlaxRobertaEmbeddings(nn.Module):
             self.config.vocab_size,
             self.config.hidden_size,
             initializer_range=self.config.initializer_range,
-            name="word_embeddings",
             dtype=self.dtype,
         )
         self.position_embeddings = FlaxRobertaEmbedding(
             self.config.max_position_embeddings,
             self.config.hidden_size,
             initializer_range=self.config.initializer_range,
-            name="position_embeddings",
             dtype=self.dtype,
         )
         self.token_type_embeddings = FlaxRobertaEmbedding(
             self.config.type_vocab_size,
             self.config.hidden_size,
             initializer_range=self.config.initializer_range,
-            name="token_type_embeddings",
             dtype=self.dtype,
         )
-        self.layer_norm = FlaxRobertaLayerNorm(
-            hidden_size=self.config.hidden_size, name="layer_norm", dtype=self.dtype
-        )
+        self.LayerNorm = FlaxRobertaLayerNorm(hidden_size=self.config.hidden_size, dtype=self.dtype)
         self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
 
     def __call__(self, input_ids, token_type_ids, position_ids, attention_mask, deterministic: bool = True):
@@ -218,38 +213,119 @@ class FlaxRobertaEmbeddings(nn.Module):
         hidden_states = inputs_embeds + jnp.broadcast_to(position_embeds, inputs_embeds.shape) + token_type_embeddings
 
         # Layer Norm
-        hidden_states = self.layer_norm(hidden_states)
+        hidden_states = self.LayerNorm(hidden_states)
         hidden_states = self.dropout(hidden_states, deterministic=deterministic)
         return hidden_states
 
 
-# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertAttention with Bert->Roberta
-class FlaxRobertaAttention(nn.Module):
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertSelfAttention with Bert->Roberta
+class FlaxRobertaSelfAttention(nn.Module):
     config: RobertaConfig
     dtype: jnp.dtype = jnp.float32  # the dtype of the computation
 
     def setup(self):
-        self.self_attention = nn.attention.SelfAttention(
-            num_heads=self.config.num_attention_heads,
-            qkv_features=self.config.hidden_size,
-            dropout_rate=self.config.attention_probs_dropout_prob,
+        if self.config.hidden_size % self.config.num_attention_heads != 0:
+            raise ValueError(
+                "`config.hidden_size`: {self.config.hidden_size} has to be a multiple of `config.num_attention_heads`: {self.config.num_attention_heads}"
+            )
+
+        self.query = nn.Dense(
+            self.config.hidden_size,
+            dtype=self.dtype,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
+        )
+        self.key = nn.Dense(
+            self.config.hidden_size,
+            dtype=self.dtype,
             kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
-            bias_init=jax.nn.initializers.zeros,
-            name="self",
+        )
+        self.value = nn.Dense(
+            self.config.hidden_size,
             dtype=self.dtype,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
         )
-        self.layer_norm = FlaxRobertaLayerNorm(
-            hidden_size=self.config.hidden_size, name="layer_norm", dtype=self.dtype
+
+    def __call__(self, hidden_states, attention_mask, deterministic=True):
+        head_dim = self.config.hidden_size // self.config.num_attention_heads
+
+        query_states = self.query(hidden_states).reshape(
+            hidden_states.shape[:2] + (self.config.num_attention_heads, head_dim)
+        )
+        value_states = self.value(hidden_states).reshape(
+            hidden_states.shape[:2] + (self.config.num_attention_heads, head_dim)
+        )
+        key_states = self.key(hidden_states).reshape(
+            hidden_states.shape[:2] + (self.config.num_attention_heads, head_dim)
+        )
+
+        # Convert the boolean attention mask to an attention bias.
+        if attention_mask is not None:
+            # attention mask in the form of attention bias
+            attention_mask = jnp.expand_dims(attention_mask, axis=(-3, -2))
+            attention_bias = lax.select(
+                attention_mask > 0,
+                jnp.full(attention_mask.shape, 0.0).astype(self.dtype),
+                jnp.full(attention_mask.shape, -1e10).astype(self.dtype),
+            )
+        else:
+            attention_bias = None
+
+        dropout_rng = None
+        if not deterministic and self.dropout_rate > 0.0:
+            dropout_rng = self.make_rng("dropout")
+
+        attn_output = dot_product_attention(
+            query_states,
+            key_states,
+            value_states,
+            bias=attention_bias,
+            dropout_rng=dropout_rng,
+            dropout_rate=self.config.attention_probs_dropout_prob,
+            broadcast_dropout=True,
+            deterministic=deterministic,
+            dtype=self.dtype,
+            precision=None,
+        )
+
+        return attn_output.reshape(attn_output.shape[:2] + (-1,))
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertSelfOutput with Bert->Roberta
+class FlaxRobertaSelfOutput(nn.Module):
+    config: RobertaConfig
+    dtype: jnp.dtype = jnp.float32  # the dtype of the computation
+
+    def setup(self):
+        self.dense = nn.Dense(
+            self.config.hidden_size,
+            kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
+            dtype=self.dtype,
         )
+        self.LayerNorm = FlaxRobertaLayerNorm(hidden_size=self.config.hidden_size)
+        self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
+
+    def __call__(self, hidden_states, input_tensor, deterministic: bool = True):
+        hidden_states = self.dense(hidden_states)
+        hidden_states = self.dropout(hidden_states, deterministic=deterministic)
+        hidden_states = self.LayerNorm(hidden_states + input_tensor)
+        return hidden_states
+
+
+# Copied from transformers.models.bert.modeling_flax_bert.FlaxBertAttention with Bert->Roberta
+class FlaxRobertaAttention(nn.Module):
+    config: RobertaConfig
+    dtype: jnp.dtype = jnp.float32
+
+    def setup(self):
+        self.self = FlaxRobertaSelfAttention(self.config, dtype=self.dtype)
+        self.output = FlaxRobertaSelfOutput(self.config, dtype=self.dtype)
 
     def __call__(self, hidden_states, attention_mask, deterministic=True):
         # Attention mask comes in as attention_mask.shape == (*batch_sizes, kv_length)
         # FLAX expects: attention_mask.shape == (*batch_sizes, 1, 1, kv_length) such that it is broadcastable
         # with attn_weights.shape == (*batch_sizes, num_heads, q_length, kv_length)
-        attention_mask = jnp.expand_dims(attention_mask, axis=(-3, -2))
-        self_attn_output = self.self_attention(hidden_states, attention_mask, deterministic=deterministic)
-
-        hidden_states = self.layer_norm(self_attn_output + hidden_states)
+        attn_output = self.self(hidden_states, attention_mask, deterministic=deterministic)
+        hidden_states = self.output(attn_output, hidden_states, deterministic=deterministic)
         return hidden_states
 
 
@@ -262,7 +338,6 @@ class FlaxRobertaIntermediate(nn.Module):
         self.dense = nn.Dense(
             self.config.intermediate_size,
             kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
-            name="dense",
             dtype=self.dtype,
         )
         self.activation = ACT2FN[self.config.hidden_act]
@@ -282,18 +357,15 @@ class FlaxRobertaOutput(nn.Module):
         self.dense = nn.Dense(
             self.config.hidden_size,
             kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
-            name="dense",
             dtype=self.dtype,
         )
         self.dropout = nn.Dropout(rate=self.config.hidden_dropout_prob)
-        self.layer_norm = FlaxRobertaLayerNorm(
-            hidden_size=self.config.hidden_size, name="layer_norm", dtype=self.dtype
-        )
+        self.LayerNorm = FlaxRobertaLayerNorm(hidden_size=self.config.hidden_size, dtype=self.dtype)
 
     def __call__(self, hidden_states, attention_output, deterministic: bool = True):
         hidden_states = self.dense(hidden_states)
         hidden_states = self.dropout(hidden_states, deterministic=deterministic)
-        hidden_states = self.layer_norm(hidden_states + attention_output)
+        hidden_states = self.LayerNorm(hidden_states + attention_output)
         return hidden_states
 
 
@@ -303,9 +375,9 @@ class FlaxRobertaLayer(nn.Module):
     dtype: jnp.dtype = jnp.float32  # the dtype of the computation
 
     def setup(self):
-        self.attention = FlaxRobertaAttention(self.config, name="attention", dtype=self.dtype)
-        self.intermediate = FlaxRobertaIntermediate(self.config, name="intermediate", dtype=self.dtype)
-        self.output = FlaxRobertaOutput(self.config, name="output", dtype=self.dtype)
+        self.attention = FlaxRobertaAttention(self.config, dtype=self.dtype)
+        self.intermediate = FlaxRobertaIntermediate(self.config, dtype=self.dtype)
+        self.output = FlaxRobertaOutput(self.config, dtype=self.dtype)
 
     def __call__(self, hidden_states, attention_mask, deterministic: bool = True):
         attention_output = self.attention(hidden_states, attention_mask, deterministic=deterministic)
@@ -336,10 +408,10 @@ class FlaxRobertaEncoder(nn.Module):
     dtype: jnp.dtype = jnp.float32  # the dtype of the computation
 
     def setup(self):
-        self.layers = FlaxRobertaLayerCollection(self.config, name="layer", dtype=self.dtype)
+        self.layer = FlaxRobertaLayerCollection(self.config, dtype=self.dtype)
 
     def __call__(self, hidden_states, attention_mask, deterministic: bool = True):
-        return self.layers(hidden_states, attention_mask, deterministic=deterministic)
+        return self.layer(hidden_states, attention_mask, deterministic=deterministic)
 
 
 # Copied from transformers.models.bert.modeling_flax_bert.FlaxBertPooler with Bert->Roberta
@@ -351,7 +423,6 @@ class FlaxRobertaPooler(nn.Module):
         self.dense = nn.Dense(
             self.config.hidden_size,
             kernel_init=jax.nn.initializers.normal(self.config.initializer_range, self.dtype),
-            name="dense",
             dtype=self.dtype,
         )
 
@@ -370,75 +441,6 @@ class FlaxRobertaPreTrainedModel(FlaxPreTrainedModel):
     config_class = RobertaConfig
     base_model_prefix = "roberta"
 
-    @staticmethod
-    def convert_from_pytorch(pt_state: Dict, config: RobertaConfig) -> Dict:
-        jax_state = dict(pt_state)
-
-        # Need to change some parameters name to match Flax names so that we don't have to fork any layer
-        for key, tensor in pt_state.items():
-            # Key parts
-            key_parts = set(key.split("."))
-
-            # Every dense layer has "kernel" parameters instead of "weight"
-            if "dense.weight" in key:
-                del jax_state[key]
-                key = key.replace("weight", "kernel")
-                jax_state[key] = tensor
-
-            # SelfAttention needs also to replace "weight" by "kernel"
-            if {"query", "key", "value"} & key_parts:
-
-                # Flax SelfAttention decomposes the heads (num_head, size // num_heads)
-                if "bias" in key:
-                    jax_state[key] = tensor.reshape((config.num_attention_heads, -1))
-                elif "weight":
-                    del jax_state[key]
-                    key = key.replace("weight", "kernel")
-                    tensor = tensor.reshape((config.num_attention_heads, -1, config.hidden_size)).transpose((2, 0, 1))
-                    jax_state[key] = tensor
-
-            # SelfAttention output is not a separate layer, remove one nesting
-            if "attention.output.dense" in key:
-                del jax_state[key]
-                key = key.replace("attention.output.dense", "attention.self.out")
-                jax_state[key] = tensor
-
-            # SelfAttention output is not a separate layer, remove nesting on layer norm
-            if "attention.output.LayerNorm" in key:
-                del jax_state[key]
-                key = key.replace("attention.output.LayerNorm", "attention.LayerNorm")
-                jax_state[key] = tensor
-
-            # There are some transposed parameters w.r.t their PyTorch counterpart
-            if "intermediate.dense.kernel" in key or "output.dense.kernel" in key:
-                jax_state[key] = tensor.T
-
-            # Self Attention output projection needs to be transposed
-            if "out.kernel" in key:
-                jax_state[key] = tensor.reshape((config.hidden_size, config.num_attention_heads, -1)).transpose(
-                    1, 2, 0
-                )
-
-            # Pooler needs to transpose its kernel
-            if "pooler.dense.kernel" in key:
-                jax_state[key] = tensor.T
-
-            # Handle LayerNorm conversion
-            if "LayerNorm" in key:
-                del jax_state[key]
-
-                # Replace LayerNorm by layer_norm
-                new_key = key.replace("LayerNorm", "layer_norm")
-
-                if "weight" in key:
-                    new_key = new_key.replace("weight", "gamma")
-                elif "bias" in key:
-                    new_key = new_key.replace("bias", "beta")
-
-                jax_state[new_key] = tensor
-
-        return jax_state
-
     def init(self, rng: jax.random.PRNGKey, input_shape: Tuple) -> FrozenDict:
         input_ids, attention_mask, token_type_ids, position_ids = self._check_inputs(
             jnp.zeros(input_shape, dtype="i4"), None, None, None
@@ -523,9 +525,9 @@ class FlaxRobertaModule(nn.Module):
     add_pooling_layer: bool = True
 
     def setup(self):
-        self.embeddings = FlaxRobertaEmbeddings(self.config, name="embeddings", dtype=self.dtype)
-        self.encoder = FlaxRobertaEncoder(self.config, name="encoder", dtype=self.dtype)
-        self.pooler = FlaxRobertaPooler(self.config, name="pooler", dtype=self.dtype)
+        self.embeddings = FlaxRobertaEmbeddings(self.config, dtype=self.dtype)
+        self.encoder = FlaxRobertaEncoder(self.config, dtype=self.dtype)
+        self.pooler = FlaxRobertaPooler(self.config, dtype=self.dtype)
 
     def __call__(self, input_ids, attention_mask, token_type_ids, position_ids, deterministic: bool = True):
 

tests/test_modeling_flax_bert.py

@@ -115,6 +115,6 @@ class FlaxBertModelTest(FlaxModelTesterMixin, unittest.TestCase):
     @slow
     def test_model_from_pretrained(self):
         for model_class_name in self.all_model_classes:
-            model = model_class_name.from_pretrained("bert-base-cased")
+            model = model_class_name.from_pretrained("bert-base-cased", from_pt=True)
             outputs = model(np.ones((1, 1)))
             self.assertIsNotNone(outputs)

tests/test_modeling_flax_common.py

@@ -27,7 +27,7 @@ if is_flax_available():
 
     import jax
     import jax.numpy as jnp
-    from transformers.modeling_flax_utils import convert_state_dict_from_pt
+    from transformers.modeling_flax_pytorch_utils import convert_pytorch_state_dict_to_flax
 
     os.environ["XLA_PYTHON_CLIENT_MEM_FRACTION"] = "0.12"  # assumed parallelism: 8
 
@@ -79,8 +79,8 @@ class FlaxModelTesterMixin:
                 pt_model_class = getattr(transformers, pt_model_class_name)
                 pt_model = pt_model_class(config).eval()
 
-                fx_state = convert_state_dict_from_pt(model_class, pt_model.state_dict(), config)
                 fx_model = model_class(config, dtype=jnp.float32)
+                fx_state = convert_pytorch_state_dict_to_flax(pt_model.state_dict(), fx_model)
                 fx_model.params = fx_state
 
                 pt_inputs = {k: torch.tensor(v.tolist()) for k, v in inputs_dict.items()}

tests/test_modeling_flax_roberta.py

@@ -115,6 +115,6 @@ class FlaxRobertaModelTest(FlaxModelTesterMixin, unittest.TestCase):
     @slow
     def test_model_from_pretrained(self):
         for model_class_name in self.all_model_classes:
-            model = model_class_name.from_pretrained("roberta-base")
+            model = model_class_name.from_pretrained("roberta-base", from_pt=True)
             outputs = model(np.ones((1, 1)))
             self.assertIsNotNone(outputs)