Revert "Defer loading hipify until it is needed (#160824)"

This reverts commit 403a3a393cda7e60f503f3b04b8805a845dcf45d.

Reverted https://github.com/pytorch/pytorch/pull/160824 on behalf of https://github.com/atalman due to Broke slow tests test_utils.py::TestHipifyTrie::test_special_char_export_trie_to_regex [GH job link](https://github.com/pytorch/pytorch/actions/runs/17387051351/job/49355619371) [HUD commit link](403a3a393c) ([comment](https://github.com/pytorch/pytorch/pull/160824#issuecomment-3243281628))

test/inductor/test_compiled_autograd.py

@@ -172,20 +172,6 @@ class TestCompiledAutograd(TestCase):
         except subprocess.CalledProcessError as e:
             self.fail(f"Subprocess exited with return code: {e.returncode}")
 
-    def test_hipify_not_loaded_with_import_torch(self):
-        script = """
-import torch
-assert globals().get("hipify", False) is False
-"""
-        self.run_as_subprocess(script)
-
-    def test_hipify_not_loaded_with_import_cpp_extension(self):
-        script = """
-import torch.utils.cpp_extension
-assert globals().get("hipify", False) is False
-"""
-        self.run_as_subprocess(script)
-
     def test_dynamo_flaky_segfault(self):
         script = """
 import torch

torch/_dynamo/compiled_autograd.py

@@ -1507,8 +1507,7 @@ def _enable(
         else:
             # we need to import this, because user might not have imported it if they directly use this context manager
             # we need to lazily import it, because of circular dependencies
-            if torch.cuda.is_available():
-                from torch._inductor import cudagraph_trees  # noqa: F401
+            import torch._inductor.cudagraph_trees
 
             (
                 prior_compiler,

torch/utils/cpp_extension.py

@@ -22,6 +22,8 @@ import torch
 import torch._appdirs
 from .file_baton import FileBaton
 from ._cpp_extension_versioner import ExtensionVersioner
+from .hipify import hipify_python
+from .hipify.hipify_python import GeneratedFileCleaner
 from typing import Optional, Union
 from typing_extensions import deprecated
 from torch.torch_version import TorchVersion, Version
@@ -1367,7 +1369,6 @@ def CUDAExtension(name, sources, *args, **kwargs):
     include_dirs = kwargs.get('include_dirs', [])
 
     if IS_HIP_EXTENSION:
-        from .hipify import hipify_python
         build_dir = os.getcwd()
         hipify_result = hipify_python.hipify(
             project_directory=build_dir,
@@ -2108,8 +2109,6 @@ def _jit_compile(name,
     if baton.try_acquire():
         try:
             if version != old_version:
-                from .hipify import hipify_python
-                from .hipify.hipify_python import GeneratedFileCleaner
                 with GeneratedFileCleaner(keep_intermediates=keep_intermediates) as clean_ctx:
                     if IS_HIP_EXTENSION and (with_cuda or with_cudnn):
                         hipify_result = hipify_python.hipify(