dynamo tracing perf: no import on hot path: 47.62 -> 47.26 (#143065)

See #143056 for overall docs.

This PR: Removed another `import` in the body of the hot path.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/143065
Approved by: https://github.com/jansel

torch/_guards.py

@@ -27,6 +27,7 @@ from typing import (
     Union,
 )
 
+import torch
 from torch.utils import _pytree as pytree
 from torch.utils._backport_slots import dataclass_slots
 from torch.utils._traceback import CapturedTraceback, format_frame
@@ -39,11 +40,6 @@ log = logging.getLogger(__name__)
 if TYPE_CHECKING:
     import sympy
 
-    # Import the following modules during type checking to enable code intelligence features,
-    # such as auto-completion in tools like pylance, even when these modules are not explicitly
-    # imported in user code.
-    import torch
-
 
 """
 torch._guards is the definitional source of truth for general purpose guard structures.
@@ -235,11 +231,10 @@ class Guard:
     def sort_key(self):
         # Put the duplicate input guards at the end. The duplicate guards have
         # two sources while guard.name only considers one source.
-        from torch._dynamo.guards import GuardBuilder
 
         is_duplicate_input = (
             isinstance(self.create_fn, functools.partial)
-            and self.create_fn.func is GuardBuilder.DUPLICATE_INPUT
+            and self.create_fn.func is torch._dynamo.guards.GuardBuilder.DUPLICATE_INPUT
         )
         return (
             is_duplicate_input,