pytorch · guilhermeleobas · Jul 29, 2025 · Jul 29, 2025 · Jul 30, 2025 · Jul 30, 2025
diff --git a/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_eq b/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_eq
diff --git a/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_ge b/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_ge
diff --git a/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_gt b/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_gt
diff --git a/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_helper_function b/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_helper_function
diff --git a/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_le b/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_le
diff --git a/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_lt b/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_lt
diff --git a/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_unary b/test/dynamo_expected_failures/CPython313-test_collections-TestCounter.test_unary
diff --git a/torch/_dynamo/polyfills/__init__.py b/torch/_dynamo/polyfills/__init__.py
@@ -24,6 +24,7 @@
     # See also the POLYFILLED_MODULE_NAMES in torch/_dynamo/polyfills/loader.py
     # Put the submodules here to avoid circular imports
     from . import (
+        _collections as _collections,
         builtins as builtins,
         functools as functools,
         itertools as itertools,

diff --git a/torch/_dynamo/polyfills/_collections.py b/torch/_dynamo/polyfills/_collections.py
@@ -0,0 +1,33 @@
+"""
+Python polyfills for builtins
+"""
+
+from collections.abc import Iterable, MutableMapping
+from typing import TypeVar
+
+from ..decorators import substitute_in_graph
+
+
+__all__ = []
+
+
+T = TypeVar("T")
+
+
+try:
+    import _collections  # type: ignore[import-not-found]
+
+    @substitute_in_graph(_collections._count_elements)
+    def _count_elements(
+        mapping: MutableMapping[T, int],
+        iterable: Iterable[T],
+    ) -> None:
+        "Tally elements from the iterable."
+        mapping_get = mapping.get
+        for elem in iterable:
+            mapping[elem] = mapping_get(elem, 0) + 1
+
+    __all__.append("_count_elements")
+
+except ImportError:
+    pass
diff --git a/torch/_dynamo/polyfills/loader.py b/torch/_dynamo/polyfills/loader.py
@@ -13,6 +13,7 @@
 
 # See also the TYPE_CHECKING block in torch/_dynamo/polyfills/__init__.py
 POLYFILLED_MODULE_NAMES: tuple[str, ...] = (
+    "_collections",
     "builtins",
     "functools",
     "itertools",

diff --git a/torch/_dynamo/variables/builtin.py b/torch/_dynamo/variables/builtin.py
@@ -2540,6 +2540,13 @@ def call_neg(self, tx: "InstructionTranslator", a):
                 (operator.neg)(a.as_proxy()),
                 sym_num=None,
             )
+
+        if (
+            isinstance(a, UserDefinedObjectVariable)
+            and a.call_obj_hasattr(tx, "__neg__").value  # type: ignore[attr-defined]
+        ):
+            return a.call_method(tx, "__neg__", [], {})
+
         # None no-ops this handler and lets the driving function proceed
         return None
 

diff --git a/torch/_dynamo/variables/user_defined.py b/torch/_dynamo/variables/user_defined.py
@@ -52,6 +52,7 @@
 from ..exc import (
     handle_observed_exception,
     ObservedAttributeError,
+    ObservedKeyError,
     raise_observed_exception,
     unimplemented_v2,
 )
@@ -1874,7 +1875,20 @@ def call_method(
     ) -> "VariableTracker":
         method = self._maybe_get_baseclass_method(name)
         if method in self._dict_methods:
-            return self._dict_vt.call_method(tx, name, args, kwargs)
+            # Dict subclasses can override __missing__ to provide fallback
+            # behavior instead of raising a KeyError. This is used, for example,
+            # by collections.Counter.
+            try:
+                return self._dict_vt.call_method(tx, name, args, kwargs)
+            except ObservedKeyError:
+                if (
+                    name == "__getitem__"
+                    and issubclass(self.python_type(), dict)
+                    and self._maybe_get_baseclass_method("__missing__")
+                ):
+                    return self.call_method(tx, "__missing__", args, kwargs)
+                else:
+                    raise
         return super().call_method(tx, name, args, kwargs)
 
     def unpack_var_sequence(self, tx):