Build XNNPACK as an ExternalProject

I believe this is necessary to support EXPORT. (We probably should not
land this unless we have a PR stacked on top of this that successfully
converts the build to EXPORT; sending this out so I can get CI going)

ghstack-source-id: 0aa08b8
ghstack-comment-id: 3067161235
Pull-Request: #12425

Author: swolchok

backends/xnnpack/CMakeLists.txt

@@ -92,9 +92,8 @@ target_include_directories(
                            ${EXECUTORCH_ROOT}/third-party/flatbuffers/include
 )
 
-set(xnnpack_third_party pthreadpool extension_threadpool cpuinfo)
-
 include(cmake/Dependencies.cmake)
+set(xnnpack_third_party XNNPACK pthreadpool extension_threadpool cpuinfo)
 
 list(TRANSFORM _xnnpack_backend__srcs PREPEND "${EXECUTORCH_ROOT}/")
 add_library(xnnpack_backend ${_xnnpack_backend__srcs})

backends/xnnpack/cmake/Dependencies.cmake

@@ -10,71 +10,84 @@ set(THIRD_PARTY_ROOT "${CMAKE_CURRENT_SOURCE_DIR}/third-party")
 
 # --- XNNPACK
 
-# Setting this global PIC flag for all XNNPACK targets. This is needed for
-# Object libraries within XNNPACK which must be PIC to successfully link this
-# static libXNNPACK
-set(ORIGINAL_CMAKE_POSITION_INDEPENDENT_CODE_FLAG
-    ${CMAKE_POSITION_INDEPENDENT_CODE}
-)
-set(CMAKE_POSITION_INDEPENDENT_CODE ON)
-
 set(XNNPACK_SOURCE_DIR "${THIRD_PARTY_ROOT}/XNNPACK")
 set(XNNPACK_INCLUDE_DIR "${XNNPACK_SOURCE_DIR}/include")
-set(XNNPACK_LIBRARY_TYPE
-    "static"
-    CACHE STRING ""
-)
-set(XNNPACK_BUILD_BENCHMARKS
-    OFF
-    CACHE BOOL ""
+
+include(ExternalProject)
+set(XNNPACK_STATIC_LIB "${CMAKE_CURRENT_BINARY_DIR}/XNNPACK/libXNNPACK.a")
+set(XNNPACK_MICROKERNELS_STATIC_LIB
+    "${CMAKE_CURRENT_BINARY_DIR}/XNNPACK/libxnnpack-microkernels-prod.a"
 )
-set(XNNPACK_BUILD_TESTS
-    OFF
-    CACHE BOOL ""
+ExternalProject_Add(
+  XNNPACKExternalProject
+  SOURCE_DIR ${XNNPACK_SOURCE_DIR}
+  # Not 100% clear on these locations
+  BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR}/XNNPACK
+  BUILD_BYPRODUCTS ${XNNPACK_STATIC_LIB} ${XNNPACK_MICROKERNELS_STATIC_LIB}
+  CMAKE_ARGS
+    -D
+    XNNPACK_LIBRARY_TYPE=static
+    -D
+    XNNPACK_BUILD_BENCHMARKS=OFF
+    -D
+    XNNPACK_BUILD_TESTS=OFF
+    -D
+    XNNPACK_ENABLE_AVXVNNI=OFF
+    # Work around observed failure:
+    # https://github.com/pytorch/executorch/pull/10362#issuecomment-2906391232
+    -D
+    XNNPACK_ENABLE_AVX512VNNIGFNI=OFF
+    -D
+    ENABLE_XNNPACK_WEIGHTS_CACHE=${EXECUTORCH_XNNPACK_ENABLE_WEIGHT_CACHE}
+    -D
+    ENABLE_XNNPACK_SHARED_WORKSPACE=${EXECUTORCH_XNNPACK_SHARED_WORKSPACE}
+    -D
+    XNNPACK_ENABLE_KLEIDIAI=${EXECUTORCH_XNNPACK_ENABLE_KLEIDIAI}
+    -D
+    CMAKE_INSTALL_PREFIX=<INSTALL_DIR>
+    -D
+    XNNPACK_BUILD_ALL_MICROKERNELS=OFF
+    -D
+    CMAKE_POSITION_INDEPENDENT_CODE=ON
 )
-set(XNNPACK_ENABLE_AVXVNNI
-    OFF
-    CACHE BOOL ""
-  )
-# Work around observed failure: https://github.com/pytorch/executorch/pull/10362#issuecomment-2906391232
-set(XNNPACK_ENABLE_AVX512VNNIGFNI
-  OFF
-  CACHE BOOL "")
 
-if(EXECUTORCH_XNNPACK_ENABLE_KLEIDI)
-    set(XNNPACK_ENABLE_KLEIDIAI
-        ON
-        CACHE BOOL ""
-    )
-else()
-    set(XNNPACK_ENABLE_KLEIDIAI
-        OFF
-        CACHE BOOL ""
-    )
-endif()
+# add_subdirectory("${XNNPACK_SOURCE_DIR}") include_directories(SYSTEM
+# ${XNNPACK_INCLUDE_DIR})
+
+add_library(XNNPACK STATIC IMPORTED GLOBAL)
+# TODO: this probably doesn't work on Windows.
+set_property(TARGET XNNPACK PROPERTY IMPORTED_LOCATION ${XNNPACK_STATIC_LIB})
 
+add_dependencies(XNNPACK XNNPACKExternalProject)
 
-set(XNNPACK_BUILD_ALL_MICROKERNELS
-    OFF
-    CACHE BOOL ""
+add_library(xnnpack-microkernels-prod STATIC IMPORTED GLOBAL)
+set_property(
+  TARGET xnnpack-microkernels-prod PROPERTY IMPORTED_LOCATION
+                                            ${XNNPACK_MICROKERNELS_STATIC_LIB}
 )
-add_subdirectory("${XNNPACK_SOURCE_DIR}")
-include_directories(SYSTEM ${XNNPACK_INCLUDE_DIR})
-list(APPEND xnnpack_third_party XNNPACK)
-install(TARGETS xnnpack-microkernels-prod
-    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
-    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
-    PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+add_dependencies(xnnpack-microkernels-prod XNNPACKExternalProject)
 
+set_target_properties(
+  XNNPACK PROPERTIES INTERFACE_LINK_LIBRARIES xnnpack-microkernels-prod
+)
+
+install(FILES ${XNNPACK_MICROKERNELS_STATIC_LIB}
+        DESTINATION ${CMAKE_INSTALL_LIBDIR}
+)
 
 if(EXECUTORCH_XNNPACK_ENABLE_KLEIDI)
-    install(TARGETS kleidiai
-        LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
-        ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
-        PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+  add_library(kleidiai SHARED IMPORTED)
+  find_library(
+    KLEIDIAI_LIBRARY kleidiai
+    PATHS "${CMAKE_CURRENT_BINARY_DIR}/XNNPACK/kleidiai-source"
+  )
+  if(not KLEIDIAI_LIBRARY)
+    message(FATAL_ERROR "Can't find KleidiAI")
+  endif()
+  install(
+    TARGETS kleidiai
+    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+  )
 endif()
-
-# Revert PIC Flag to what it originally was
-set(CMAKE_POSITION_INDEPENDENT_CODE
-    ${ORIGINAL_CMAKE_POSITION_INDEPENDENT_CODE_FLAG}
-)

tools/cmake/executorch-config.cmake

@@ -78,11 +78,6 @@ set(lib_list
     extension_threadpool
     extension_training
     xnnpack_backend
-    # Start XNNPACK Lib Deps
-    XNNPACK
-    xnnpack-microkernels-prod
-    kleidiai
-    # End XNNPACK Lib Deps
     cpuinfo
     pthreadpool
     vulkan_backend
@@ -150,7 +145,9 @@ if(TARGET coremldelegate)
 endif()
 
 if(TARGET etdump)
-  set_target_properties(etdump PROPERTIES INTERFACE_LINK_LIBRARIES "flatccrt;executorch")
+  set_target_properties(
+    etdump PROPERTIES INTERFACE_LINK_LIBRARIES "flatccrt;executorch"
+  )
 endif()
 
 if(TARGET optimized_native_cpu_ops_lib)
@@ -174,13 +171,11 @@ if(TARGET extension_threadpool)
 endif()
 
 set(shared_lib_list
-  # executorch -- size tests fail due to regression if we include this and I'm not sure it's needed.
-  optimized_native_cpu_ops_lib
-  portable_ops_lib
-  quantized_ops_lib
-  xnnpack_backend
-  vulkan_backend
-  quantized_ops_aot_lib)
+    # executorch -- size tests fail due to regression if we include this and I'm
+    # not sure it's needed.
+    optimized_native_cpu_ops_lib portable_ops_lib quantized_ops_lib
+    xnnpack_backend vulkan_backend quantized_ops_aot_lib
+)
 foreach(lib ${shared_lib_list})
   if(TARGET ${lib})
     target_link_options_shared_lib(${lib})