Disable the MLIR ExecutionEngine library when the native target is not configured

[mehdi_amini]

Summary

The execution engine would not be functional anyway, we're already
disabling the tests, this also disable the rest of the code.

Anecdotally this reduces the number of static library built when the
builtin target is disabled goes from 236 to 218.

Here is the complete list of LLVM targets built when running
ninja check-mlir:

libLLVMAggressiveInstCombine.a
libLLVMAnalysis.a
libLLVMAsmParser.a
libLLVMBinaryFormat.a
libLLVMBitReader.a
libLLVMBitstreamReader.a
libLLVMBitWriter.a
libLLVMCore.a
libLLVMDebugInfoCodeView.a
libLLVMDebugInfoDWARF.a
libLLVMDemangle.a
libLLVMFileCheck.a
libLLVMFrontendOpenMP.a
libLLVMInstCombine.a
libLLVMIRReader.a
libLLVMMC.a
libLLVMMCParser.a
libLLVMObject.a
libLLVMProfileData.a
libLLVMRemarks.a
libLLVMScalarOpts.a
libLLVMSupport.a
libLLVMTableGen.a
libLLVMTableGenGlobalISel.a
libLLVMTextAPI.a
libLLVMTransformUtils.a

[stephenneuendorffer]

Thanks for this!

mlir/lib/CAPI/CMakeLists.txt

18–22

If cross-compiling, would this disable the ExecutionEngine? I'm not sure what the semantics of LLVM_NATIVE_ARCH is.

[mehdi_amini]

mlir/lib/CAPI/CMakeLists.txt

18–22

You're right, that won't be the right thing to do...
Maybe we should hook to when -DLLVM_DEFAULT_TARGET_TRIPLE="" instead then. I'll look into this tomorrow

[stephenneuendorffer]

mlir/lib/CAPI/CMakeLists.txt

18–22

I think this is correct when cross-compiling, since it is set from LLVM_TARGET_ARCH, which should be set to the architecture being cross-compiled for.

[mehdi_amini]

mlir/lib/CAPI/CMakeLists.txt

18–22

Actually LLVM_NATIVE_ARCH is the crossed-compiled target, so we're fine here.

[jpienaar]

OOC why is libLLVMIRReader.a built without a target config? (One can built it without, but I'm not sure where it would be used)

[mehdi_amini]

In D117287#3243200, @jpienaar wrote:

OOC why is libLLVMIRReader.a built without a target config? (One can built it without, but I'm not sure where it would be used)

“Target” are the LLVM backends, without a target we lose the ability to JIT or emit native code in general, but can still import/export LLVM IR!

mlir/lib/CAPI/CMakeLists.txt

 # For upstream, we accumulate all libraries into the MLIR_CAPI_LIBRARIES
 # property via a custom wrapper function. This is then used to create an
 # aggregate below.
 set_property(GLOBAL APPEND PROPERTY MLIR_CAPI_LIBRARIES)
 function(add_mlir_upstream_c_api_library name)
   add_mlir_public_c_api_library(${name} ${ARGN})
   set_property(GLOBAL APPEND PROPERTY MLIR_CAPI_LIBRARIES ${name})
 endfunction()
 
 add_subdirectory(Debug)
 add_subdirectory(Dialect)
 add_subdirectory(Conversion)
-add_subdirectory(ExecutionEngine)
 add_subdirectory(Interfaces)
 add_subdirectory(IR)
 add_subdirectory(Registration)
 add_subdirectory(Transforms)
 
+# Only enable the ExecutionEngine if the native target is configured in.
+if(TARGET ${LLVM_NATIVE_ARCH})
+  add_subdirectory(ExecutionEngine)
+endif()
+
 # Build the optional CAPI dylib.
 if(MLIR_BUILD_MLIR_C_DYLIB)
   message(STATUS "Building MLIR-C dylib")
   get_property(_capi_libraries GLOBAL PROPERTY MLIR_CAPI_LIBRARIES)
   add_mlir_aggregate(MLIR-C
     SHARED
     EMBED_LIBS
       ${_capi_libraries}
   )
   if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
     target_link_options(MLIR-C PRIVATE "-Wl,-exclude-libs,ALL")
   else()
     if(NOT CMAKE_C_VISIBILITY_PRESET STREQUAL "hidden" OR NOT CMAKE_CXX_VISIBILITY_PRESET STREQUAL "hidden")
       message(STATUS "MLIR-C on this platform exports all symbols. Recommend building with CMAKE_(C|CXX)_VISIBILITY_PRESET=hidden or implement filtering support.")
     endif()
   endif()
 endif()
+

mlir/lib/CMakeLists.txt

 # Enable errors for any global constructors.
 add_flag_if_supported("-Werror=global-constructors" WERROR_GLOBAL_CONSTRUCTOR)
 
 add_subdirectory(Analysis)
 add_subdirectory(Conversion)
 add_subdirectory(Dialect)
-add_subdirectory(ExecutionEngine)
 add_subdirectory(IR)
 add_subdirectory(Interfaces)
 add_subdirectory(Parser)
 add_subdirectory(Pass)
 add_subdirectory(Reducer)
 add_subdirectory(Rewrite)
 add_subdirectory(Support)
 add_subdirectory(TableGen)
 add_subdirectory(Target)
 add_subdirectory(Tools)
 add_subdirectory(Transforms)
 add_subdirectory(Translation)
+
+# Only enable the ExecutionEngine if the native target is configured in.
+if(TARGET ${LLVM_NATIVE_ARCH})
+  add_subdirectory(ExecutionEngine)
+endif()
 No newline at end of file

mlir/python/CMakeLists.txt

declare_mlir_python_extension(MLIRPythonExtension.Conversions
   SOURCES
     Conversions/Conversions.cpp
   PRIVATE_LINK_LIBS
     LLVMSupport
   EMBED_CAPI_LINK_LIBS
   MLIRCAPIConversion
 )
 
+# Only enable the ExecutionEngine if the native target is configured in.
+if(TARGET ${LLVM_NATIVE_ARCH})
   declare_mlir_python_extension(MLIRPythonExtension.ExecutionEngine
     MODULE_NAME _mlirExecutionEngine
     ADD_TO_PARENT MLIRPythonSources.ExecutionEngine
     ROOT_DIR "${PYTHON_SOURCE_DIR}"
     SOURCES
       ExecutionEngineModule.cpp
     PRIVATE_LINK_LIBS
       LLVMSupport
     EMBED_CAPI_LINK_LIBS
       MLIRCAPIExecutionEngine
   )
+endif()
 
 declare_mlir_python_extension(MLIRPythonExtension.GPUDialectPasses
   MODULE_NAME _mlirGPUPasses
   ADD_TO_PARENT MLIRPythonSources.Dialects.gpu
   ROOT_DIR "${PYTHON_SOURCE_DIR}"
   SOURCES
     GPUPasses.cpp
   PRIVATE_LINK_LIBS

mlir/test/CAPI/CMakeLists.txt

if(MLIR_BUILD_MLIR_C_DYLIB)
     target_link_libraries(${name} PRIVATE
       MLIR-C)
   else()
     target_link_libraries(${name} PRIVATE
       ${ARG_LINK_LIBS})
   endif()
 endfunction(_add_capi_test_executable)
 
+# Only enable the ExecutionEngine if the native target is configured in.
+if(TARGET ${LLVM_NATIVE_ARCH})
   _add_capi_test_executable(mlir-capi-execution-engine-test
     execution_engine.c
   LINK_LIBS PRIVATE
     MLIRCAPIConversion
     MLIRCAPIExecutionEngine
     MLIRCAPIRegistration
   )
+endif()
 
 _add_capi_test_executable(mlir-capi-ir-test
   ir.c
   LINK_LIBS PRIVATE
     MLIRCAPIIR
     MLIRCAPIStandard
     MLIRCAPIRegistration
 )

mlir/test/CMakeLists.txt

configure_lit_site_cfg(
   ${CMAKE_CURRENT_SOURCE_DIR}/Unit/lit.site.cfg.py.in
   ${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg.py
   MAIN_CONFIG
   ${CMAKE_CURRENT_SOURCE_DIR}/Unit/lit.cfg.py
   )
 
 set(MLIR_TEST_DEPENDS
   FileCheck count not split-file
-  mlir-capi-execution-engine-test
   mlir-capi-ir-test
   mlir-capi-llvm-test
   mlir-capi-pass-test
   mlir-capi-sparse-tensor-test
   mlir-capi-quant-test
   mlir-capi-pdl-test
   mlir-linalg-ods-yaml-gen
   mlir-lsp-server
   mlir-opt
   mlir-pdll
   mlir-reduce
   mlir-tblgen
   mlir-translate
-  mlir_runner_utils
-  mlir_c_runner_utils
-  mlir_async_runtime
   )
 
 # The native target may not be enabled, in this case we won't
 # run tests that involves executing on the host: do not build
 # useless binaries.
 if(TARGET ${LLVM_NATIVE_ARCH})
   list(APPEND MLIR_TEST_DEPENDS
     mlir-cpu-runner
     llc
+    mlir_async_runtime
+    mlir-capi-execution-engine-test
+    mlir_c_runner_utils
+    mlir_runner_utils
   )
 endif()
 
 if (MLIR_INCLUDE_INTEGRATION_TESTS)
   list(APPEND MLIR_TEST_DEPENDS lli)
 endif()
 
 if(MLIR_ENABLE_CUDA_RUNNER)