Redefine TorchMLIRPythonModules to avoid building empty libraries. (#…

…3711)

Trying to build empty libraries causes weird failures based on clang/gcc
and doesn't work with certain versions of python as well. We should
avoid this wherever possible, and this specifically has been leading to
the following issues/failures:

#3663

https://github.com/llvm/torch-mlir-release/actions/runs/10558518843/job/29248139823

CMakeLists.txt

@@ -51,6 +51,9 @@ option(TORCH_MLIR_OUT_OF_TREE_BUILD "Specifies an out of tree build" OFF)
 # But it will be manually enabled in CI build to enable the jit_ir_importer.build_tools.torch_ods_gen
 # and abstract_interp_lib_gen.py. Once pure python version of build_tools finished, no need to set it in CI.
 option(TORCH_MLIR_ENABLE_PYTORCH_EXTENSIONS "Enables PyTorch native extension features" OFF)
+if(TORCH_MLIR_ENABLE_PYTORCH_EXTENSIONS)
+  add_definitions(-DTORCH_MLIR_ENABLE_PYTORCH_EXTENSIONS)
+endif()
 # NOTE: The JIT_IR_IMPORTER paths have become unsupportable due to age and lack of maintainers.
 # Turning this off disables the old TorchScript path, leaving FX based import as the current supported option.
 # The option will be retained for a time, and if a maintainer is interested in setting up testing for it,

python/CMakeLists.txt

@@ -96,16 +96,18 @@ set(_source_components
   TorchMLIRPythonSources
   TorchMLIRPythonExtensions
   TorchMLIRSiteInitialize
-
-  # Sources related to optional Torch extension dependent features. Typically
-  # empty unless if project features are enabled.
-  TorchMLIRPythonTorchExtensionsSources
 )
 
 if(TORCH_MLIR_ENABLE_STABLEHLO)
   list(APPEND _source_components StablehloPythonExtensions)
 endif()
 
+# Sources related to optional Torch extension dependent features. Typically
+# empty unless if project features are enabled.
+if(TORCH_MLIR_ENABLE_PYTORCH_EXTENSIONS)
+  list(APPEND _source_components TorchMLIRPythonTorchExtensionsSources)
+endif()
+
 add_mlir_python_common_capi_library(TorchMLIRAggregateCAPI
   INSTALL_COMPONENT TorchMLIRPythonModules
   INSTALL_DESTINATION python_packages/torch_mlir/torch_mlir/_mlir_libs

setup.py

@@ -75,7 +75,7 @@ def _check_env_flag(name: str, default=None) -> bool:
 # If true, enable LTC build by default
 TORCH_MLIR_ENABLE_LTC = _check_env_flag("TORCH_MLIR_ENABLE_LTC", True)
 TORCH_MLIR_ENABLE_ONLY_MLIR_PYTHON_BINDINGS = _check_env_flag(
-    "TORCH_MLIR_ENABLE_ONLY_MLIR_PYTHON_BINDINGS", False
+    "TORCH_MLIR_ENABLE_ONLY_MLIR_PYTHON_BINDINGS", True
 )
 LLVM_INSTALL_DIR = os.getenv("LLVM_INSTALL_DIR", None)
 SRC_DIR = pathlib.Path(__file__).parent.absolute()