[torch.compile] Disable recursive pre_grad_passes (#34092)

Signed-off-by: Richard Zou <zou3519@gmail.com>

vllm/compilation/compiler_interface.py

@@ -257,7 +257,20 @@ class InductorStandaloneAdaptor(CompilerInterface):
         if use_aot:
             compile_kwargs["aot"] = True  # type: ignore[assignment]
 
-        compiled_graph = standalone_compile(graph, example_inputs, **compile_kwargs)
+        # Inductor's pre-grad passes don't do anything for vLLM.
+        # The pre-grad passes get run even on cache-hit and negatively impact
+        # vllm cold compile times by O(1s)
+        # Can remove this after the following issue gets fixed
+        # https://github.com/pytorch/pytorch/issues/174502
+        if envs.VLLM_ENABLE_PREGRAD_PASSES:
+            ctx: Any = contextlib.nullcontext()
+        else:
+            ctx = patch(
+                "torch._inductor.compile_fx._recursive_pre_grad_passes",
+                lambda gm, _: gm,
+            )
+        with ctx:
+            compiled_graph = standalone_compile(graph, example_inputs, **compile_kwargs)
 
         if use_aot:
             from torch._inductor.standalone_compile import AOTCompiledArtifact