standalone find_batch_size_dim (#1005)

Summary:
Pull Request resolved: #1005

`find_batch_size_dim` is a common util being used outside of fx2ait

This diff is making this util as a standalone python_library so we don't need to depends on the entire fx2ait lib

Reviewed By: qxy11

Differential Revision: D56989131

fbshipit-source-id: ab6fa1bd1b7dad484ef2b4ee60c168ad7993ef1f

fx2ait/fx2ait/find_batch_size_dim.py

@@ -0,0 +1,86 @@
+#  Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+#  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.
+#
+from typing import Any
+
+import torch
+
+
+def find_batch_size_dim(
+    inputs: Any,
+    can_non_first_dim_be_dynamic: bool = True,
+    can_dim_value_one_be_dynamic: bool = True,
+    # pyre-fixme Invalid type [31]
+) -> []:
+    if isinstance(inputs, torch.Tensor) or len(inputs) <= 1:
+        return [0]
+    shapes = [i.shape for i in inputs]
+    frequency_map = {}
+    position_scores = {}
+    first_dims = set()
+    for shape in shapes:
+        if len(shape) < 2:
+            # By pass for rank-1 tensors. MRS model has rank-1 tensor carry no batch_size info
+            continue
+        # Dedup shape value for single tensor
+        first_dims.add(shape[0])
+        seen_dims = set()
+        valid_len = len(shape) if can_non_first_dim_be_dynamic else 1
+        for i in range(valid_len):
+            dim = shape[i]
+            if dim not in seen_dims:
+                frequency_map[dim] = frequency_map.get(dim, 0) + 1
+                position_scores[dim] = position_scores.get(dim, 0) + i
+                seen_dims.add(dim)
+
+    if len(first_dims) == 1:
+        # first dim is the same in every input: we use it as batch_size
+        batch_size = first_dims.pop()
+    elif frequency_map:
+        # first dims are different: we use the most frequent dim as batch_size
+        # if there is more than 1 most frequent dim, we choose the one with the
+        # lowest position score (i.e., the leftmost of the most frequent ones)
+        sorted_frequency = sorted(
+            frequency_map.items(),
+            key=lambda x: (-x[1], position_scores[x[0]]),
+        )
+        if len(sorted_frequency) > 1:
+            if not can_dim_value_one_be_dynamic and sorted_frequency[0][0] == 1:
+                # It's often that dim value one indicates a non-dynamic dimension.
+                # If the user says so, we pick the second most frequent value.
+                batch_size = sorted_frequency[1][0]
+            else:
+                batch_size = sorted_frequency[0][0]
+        else:
+            if not can_dim_value_one_be_dynamic and sorted_frequency[0][0] == 1:
+                batch_size = -1
+            else:
+                batch_size = sorted_frequency[0][0]
+    else:
+        # no dims to sort: no batch_size
+        batch_size = -1
+
+    bs_dim = []
+    for i in inputs:
+        # Default batch size dim = -1, indicate no batch_size
+        dim = -1
+        for index, val in enumerate(i.shape):
+            if not can_non_first_dim_be_dynamic and index > 0:
+                break
+            if val == batch_size:
+                dim = index
+                break
+        bs_dim.append(dim)
+
+    return bs_dim

fx2ait/fx2ait/tensor_spec.py

@@ -18,6 +18,8 @@
 import torch
 from aitemplate.compiler.public import IntImm, IntVar
 
+from .find_batch_size_dim import find_batch_size_dim as find_batch_size_dim_impl
+
 logger: logging.Logger = logging.getLogger(__name__)
 
 
@@ -475,68 +477,11 @@ def find_batch_size_dim(
         inputs: Any,
         can_non_first_dim_be_dynamic: bool = True,
         can_dim_value_one_be_dynamic: bool = True,
+        # pyre-fixme Invalid type [31]
     ) -> []:
-        if isinstance(inputs, torch.Tensor) or len(inputs) <= 1:
-            return [0]
-        shapes = [i.shape for i in inputs]
-        frequency_map = {}
-        position_scores = {}
-        first_dims = set()
-        for shape in shapes:
-            if len(shape) < 2:
-                # By pass for rank-1 tensors. MRS model has rank-1 tensor carry no batch_size info
-                continue
-            # Dedup shape value for single tensor
-            first_dims.add(shape[0])
-            seen_dims = set()
-            valid_len = len(shape) if can_non_first_dim_be_dynamic else 1
-            for i in range(valid_len):
-                dim = shape[i]
-                if dim not in seen_dims:
-                    frequency_map[dim] = frequency_map.get(dim, 0) + 1
-                    position_scores[dim] = position_scores.get(dim, 0) + i
-                    seen_dims.add(dim)
-
-        if len(first_dims) == 1:
-            # first dim is the same in every input: we use it as batch_size
-            batch_size = first_dims.pop()
-        elif frequency_map:
-            # first dims are different: we use the most frequent dim as batch_size
-            # if there is more than 1 most frequent dim, we choose the one with the
-            # lowest position score (i.e., the leftmost of the most frequent ones)
-            sorted_frequency = sorted(
-                frequency_map.items(),
-                key=lambda x: (-x[1], position_scores[x[0]]),
-            )
-            if len(sorted_frequency) > 1:
-                if not can_dim_value_one_be_dynamic and sorted_frequency[0][0] == 1:
-                    # It's often that dim value one indicates a non-dynamic dimension.
-                    # If the user says so, we pick the second most frequent value.
-                    batch_size = sorted_frequency[1][0]
-                else:
-                    batch_size = sorted_frequency[0][0]
-            else:
-                if not can_dim_value_one_be_dynamic and sorted_frequency[0][0] == 1:
-                    batch_size = -1
-                else:
-                    batch_size = sorted_frequency[0][0]
-        else:
-            # no dims to sort: no batch_size
-            batch_size = -1
-
-        bs_dim = []
-        for i in inputs:
-            # Default batch size dim = -1, indicate no batch_size
-            dim = -1
-            for index, val in enumerate(i.shape):
-                if not can_non_first_dim_be_dynamic and index > 0:
-                    break
-                if val == batch_size:
-                    dim = index
-                    break
-            bs_dim.append(dim)
-
-        return bs_dim
+        return find_batch_size_dim_impl(
+            inputs, can_non_first_dim_be_dynamic, can_dim_value_one_be_dynamic
+        )
 
     @classmethod
     def from_input_list_with_batch_size_static_batch(