[Dynamo] Mark config.dead_code_elimination as deprecated (#136933)

shink · pytorchmergebot · commit be169f743b43 · 2024-10-01T03:51:59.000Z
part of #136862 For reviewers, all call sites are here: https://github.com/search?q=repo%3Apytorch%2Fpytorch+dead_code_elimination+language%3APython&type=code&l=Python Pull Request resolved: #136933 Approved by: https://github.com/williamwen42, https://github.com/anijain2305
diff --git a/test/dynamo/test_config.py b/test/dynamo/test_config.py
@@ -96,9 +96,9 @@ def test_config_hash(self):
         new_hash = config.get_hash()
         assert new_hash == starting_hash
 
-        with config.patch({"dead_code_elimination": not config.dead_code_elimination}):
+        with config.patch({"suppress_errors": not config.suppress_errors}):
             changed_hash = config.get_hash()
-            assert "dead_code_elimination" not in config._compile_ignored_keys
+            assert "suppress_errors" not in config._compile_ignored_keys
             assert changed_hash != starting_hash
 
             # Test nested patch
diff --git a/torch/_dynamo/config.py b/torch/_dynamo/config.py
@@ -31,7 +31,7 @@
 # need this many ops to create an FX graph
 minimum_call_count = 1
 
-# turn on/off DCE pass
+# turn on/off DCE pass (deprecated: always true)
 dead_code_elimination = True
 
 # disable (for a function) when cache reaches this size
diff --git a/torch/_dynamo/convert_frame.py b/torch/_dynamo/convert_frame.py
@@ -17,6 +17,7 @@
 import time
 import traceback
 import typing
+import warnings
 import weakref
 from pathlib import Path
 from types import CodeType, FrameType, FunctionType, ModuleType
@@ -656,10 +657,16 @@ def transform(
         instructions[:] = output.output_instructions
         code_options.update(output.code_options)
 
-        if config.dead_code_elimination:
-            propagate_inst_exn_table_entries(instructions)
-            check_inst_exn_tab_entries_valid(instructions)
-            instructions[:] = remove_pointless_jumps(remove_dead_code(instructions))
+        # The config.dead_code_elimination flag is deprecated
+        # See https://github.com/pytorch/pytorch/issues/136862 for more information
+        if not config.dead_code_elimination:
+            warnings.warn(
+                "The config.dead_code_elimination flag is deprecated, it's now always true."
+            )
+
+        propagate_inst_exn_table_entries(instructions)
+        check_inst_exn_tab_entries_valid(instructions)
+        instructions[:] = remove_pointless_jumps(remove_dead_code(instructions))
 
     def compile_inner(
         code: CodeType,
