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cmake(pt): robustly detect PyTorch CXX11 ABI via Python; unify comments #4879

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cmake(pt): robustly detect PyTorch CXX11 ABI via Python; unify comments #4879

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8789c35
fix: update CMakeLists.txt to support PyTorch CXX11 ABI check for Pyt…
OutisLi Aug 11, 2025
8df2203
typo fix
OutisLi Aug 11, 2025
222d9ee
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Aug 11, 2025
5750130
add fall back to a safe default
OutisLi Aug 11, 2025
cdda058
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Aug 11, 2025
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103 changes: 68 additions & 35 deletions source/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -303,6 +303,7 @@ if(ENABLE_TENSORFLOW AND NOT DEEPMD_C_ROOT)
list(APPEND BACKEND_LIBRARY_PATH ${TensorFlow_LIBRARY_PATH})
list(APPEND BACKEND_INCLUDE_DIRS ${TENSORFLOW_INCLUDE_DIRS})
endif()

if(BUILD_CPP_IF
AND USE_PT_PYTHON_LIBS
AND NOT CMAKE_CROSSCOMPILING
Expand All @@ -327,57 +328,88 @@ if(BUILD_CPP_IF
endif()
list(APPEND CMAKE_PREFIX_PATH ${PYTORCH_CMAKE_PREFIX_PATH})
endif()

if(ENABLE_PYTORCH AND NOT DEEPMD_C_ROOT)
find_package(Torch REQUIRED)
if(NOT Torch_VERSION VERSION_LESS "2.1.0")
set_if_higher(CMAKE_CXX_STANDARD 17)
elseif(NOT Torch_VERSION VERSION_LESS "1.5.0")
set_if_higher(CMAKE_CXX_STANDARD 14)
endif()
string(REGEX MATCH "_GLIBCXX_USE_CXX11_ABI=([0-9]+)" CXXABI_PT_MATCH
"${TORCH_CXX_FLAGS}")
if(CXXABI_PT_MATCH)
set(OP_CXX_ABI_PT ${CMAKE_MATCH_1})
message(STATUS "PyTorch CXX11 ABI: ${CMAKE_MATCH_1}")
if(DEFINED OP_CXX_ABI)
if(NOT ${CMAKE_MATCH_1} EQUAL ${OP_CXX_ABI})
if(NOT BUILD_PY_IF)

# detect PyTorch CXX11 ABI via Python
message(STATUS "Detecting PyTorch CXX11 ABI via Python API...")
find_package(
Python
COMPONENTS Interpreter
REQUIRED)
message(STATUS "Using Python executable: ${Python_EXECUTABLE}")

execute_process(
COMMAND env PYTHONPATH=${Python_SITEARCH} ${Python_EXECUTABLE} -c
"import torch; print(int(torch.compiled_with_cxx11_abi()))"
OUTPUT_VARIABLE DETECTED_PT_ABI
RESULT_VARIABLE pt_abi_result
OUTPUT_STRIP_TRAILING_WHITESPACE)

Comment on lines +348 to +354
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@coderabbitai coderabbitai bot Aug 11, 2025

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🛠️ Refactor suggestion

⚠️ Potential issue

Make Python call portable and resilient (no 'env', avoid Python_SITEARCH dependency)

  • Using env in execute_process(COMMAND ...) breaks on Windows. Use ENVIRONMENT instead.
  • Python_SITEARCH is not guaranteed when only the Interpreter component is found. It can be empty and isn’t needed to import torch from the active interpreter.
-  execute_process(
-    COMMAND env PYTHONPATH=${Python_SITEARCH} ${Python_EXECUTABLE} -c
-            "import torch; print(int(torch.compiled_with_cxx11_abi()))"
-    OUTPUT_VARIABLE DETECTED_PT_ABI
-    RESULT_VARIABLE pt_abi_result
-    OUTPUT_STRIP_TRAILING_WHITESPACE)
+  execute_process(
+    COMMAND ${Python_EXECUTABLE} -c "import torch; print(int(torch.compiled_with_cxx11_abi()))"
+    OUTPUT_VARIABLE DETECTED_PT_ABI
+    RESULT_VARIABLE pt_abi_result
+    ERROR_VARIABLE pt_abi_err
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+    # If you still need to influence sys.path, do it via ENVIRONMENT (portable):
+    # ENVIRONMENT "PYTHONPATH=${Python_SITEARCH}"
+  )

Optional: If you want to prefer the active interpreter’s environment, drop PYTHONPATH entirely (as above). If you keep it, gate it with if(DEFINED Python_SITEARCH).

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
execute_process(
COMMAND env PYTHONPATH=${Python_SITEARCH} ${Python_EXECUTABLE} -c
"import torch; print(int(torch.compiled_with_cxx11_abi()))"
OUTPUT_VARIABLE DETECTED_PT_ABI
RESULT_VARIABLE pt_abi_result
OUTPUT_STRIP_TRAILING_WHITESPACE)
execute_process(
COMMAND ${Python_EXECUTABLE} -c "import torch; print(int(torch.compiled_with_cxx11_abi()))"
OUTPUT_VARIABLE DETECTED_PT_ABI
RESULT_VARIABLE pt_abi_result
ERROR_VARIABLE pt_abi_err
OUTPUT_STRIP_TRAILING_WHITESPACE
# If you still need to influence sys.path, do it via ENVIRONMENT (portable):
# ENVIRONMENT "PYTHONPATH=${Python_SITEARCH}"
)
🤖 Prompt for AI Agents 
In source/CMakeLists.txt around lines 348 to 354, the execute_process invocation
uses a platform-unsafe "env" wrapper and unconditionally sets PYTHONPATH to
Python_SITEARCH which may be empty; change it to call the interpreter directly
via ${Python_EXECUTABLE} and supply environment variables via CMake's
ENVIRONMENT keyword (not the "env" command) or simply drop PYTHONPATH entirely
to prefer the active interpreter’s environment; if you must set PYTHONPATH,
guard it with if(DEFINED Python_SITEARCH) and only add ENVIRONMENT
"PYTHONPATH=${Python_SITEARCH}" when defined so the command is portable on
Windows and resilient when Python_SITEARCH is missing.

if(pt_abi_result EQUAL 0)
# python command succeeded
set(OP_CXX_ABI_PT ${DETECTED_PT_ABI})
message(STATUS "Detected PyTorch CXX11 ABI: ${OP_CXX_ABI_PT}")
else()
# Python torch not available -> warn and default
string(REGEX MATCH "-D_GLIBCXX_USE_CXX11_ABI=([01])" _m
"${CMAKE_CXX_FLAGS}")
if(CMAKE_MATCH_1)
set(OP_CXX_ABI_PT "${CMAKE_MATCH_1}")
message(
STATUS "Parsed PyTorch CXX11 ABI from CMAKE_CXX_FLAGS: ${OP_CXX_ABI_PT}"
)
else()
message(
WARNING
"Could not detect PyTorch CXX11 ABI (torch import failed with code=${pt_abi_result}). "
"Defaulting OP_CXX_ABI_PT=1.")
set(OP_CXX_ABI_PT 1)
endif()
endif()

if(DEFINED OP_CXX_ABI)
# if ABI was previously set (e.g., from TensorFlow), check mismatch
if(NOT ${OP_CXX_ABI_PT} EQUAL ${OP_CXX_ABI})
if(NOT BUILD_PY_IF)
message(
FATAL_ERROR
"PyTorch CXX11 ABI mismatch TensorFlow: ${OP_CXX_ABI_PT} != ${OP_CXX_ABI}"
)
else()
if(NOT BUILD_CPP_IF)
message(
FATAL_ERROR
"PyTorch CXX11 ABI mismatch TensorFlow: ${CMAKE_MATCH_1} != ${OP_CXX_ABI}"
)
STATUS
"PyTorch CXX11 ABI mismatch TensorFlow: ${OP_CXX_ABI_PT} != ${OP_CXX_ABI}. "
"Try to build libraries with both ABIs.")
else()
if(NOT BUILD_CPP_IF)
message(
STATUS
"PyTorch CXX11 ABI mismatch TensorFlow: ${CMAKE_MATCH_1} != ${OP_CXX_ABI}. "
"Try to build libraries with both ABIs.")
else()
message(
WARNING
"PyTorch CXX11 ABI mismatch TensorFlow: ${CMAKE_MATCH_1} != ${OP_CXX_ABI}. "
"PyTorch C++ OP will be built but PyTorch support for C++ libraries will be disabled. "
"Note that we don't officially support building C++ libraries in the Python package, "
"except for the wheels we officially release.")
endif()
set(DEEPMD_BUILD_COMPAT_CXXABI ON)
set(OP_CXX_ABI_COMPAT ${OP_CXX_ABI_PT})
message(
WARNING
"PyTorch CXX11 ABI mismatch TensorFlow: ${OP_CXX_ABI_PT} != ${OP_CXX_ABI}. "
"PyTorch C++ OP will be built but PyTorch support for C++ libraries will be disabled. "
"Note that we don't officially support building C++ libraries in the Python package, "
"except for the wheels we officially release.")
endif()
else()
set(DEEPMD_BUILD_COMPAT_CXXABI OFF)
set(DEEPMD_BUILD_COMPAT_CXXABI ON)
set(OP_CXX_ABI_COMPAT ${OP_CXX_ABI_PT})
endif()
else()
set(OP_CXX_ABI ${CMAKE_MATCH_1})
# ABI matches; no compat build needed
set(DEEPMD_BUILD_COMPAT_CXXABI OFF)
add_definitions(-D_GLIBCXX_USE_CXX11_ABI=${OP_CXX_ABI})
endif()
else()
# Maybe in macos/windows
if(NOT DEFINED OP_CXX_ABI)
set(OP_CXX_ABI 0)
endif()
set(OP_CXX_ABI_PT "${OP_CXX_ABI}")
# no prior ABI; default to PyTorch ABI
set(OP_CXX_ABI ${OP_CXX_ABI_PT})
add_definitions(-D_GLIBCXX_USE_CXX11_ABI=${OP_CXX_ABI})
endif()
# get torch directory get the directory of the target "torch"
# get torch library directory from target "torch"
get_target_property(_TORCH_LOCATION torch LOCATION)
get_filename_component(PyTorch_LIBRARY_PATH ${_TORCH_LOCATION} DIRECTORY)
list(APPEND BACKEND_LIBRARY_PATH ${PyTorch_LIBRARY_PATH})
Expand All @@ -387,6 +419,7 @@ if(ENABLE_PYTORCH AND NOT DEEPMD_C_ROOT)
link_directories(${PyTorch_LIBRARY_PATH}/../../torch.libs)
endif()
endif()

if(ENABLE_JAX
AND BUILD_CPP_IF
AND NOT DEEPMD_C_ROOT)
Expand Down
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