Add EXECUTORCH_BUILD_HOST_TARGETS option to guard host-only targets (#463)

dbort · facebook-github-bot · commit 57142858eb36 · 2023-09-26T12:09:13.000-07:00
Summary: Pull Request resolved: #463 When cross-compiling in CMake, users would like a way to avoid building host-only targets. Introduce a general mechanism to disable building targets like these. Also update the set of vars printed by Utils.cmake, and format/lint it. ghstack-source-id: 201888044 exported-using-ghexport Reviewed By: tarun292, cccclai Differential Revision: D49558464 fbshipit-source-id: 935ea7e10e02f7492bf2a343998ae38cc70f13ba
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -44,11 +44,17 @@ cmake_minimum_required(VERSION 3.19)
 project(executorch)
 include(build/Utils.cmake)
 
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+if(NOT CMAKE_CXX_STANDARD)
+  set(CMAKE_CXX_STANDARD 17)
+endif()
+
 if(NOT CMAKE_BUILD_TYPE)
   set(CMAKE_BUILD_TYPE Debug)
 endif()
-# -Os: Optimize for size -ffunction-sections -fdata-sections: breaks function
-# and data into sections so they can be properly gc'd -s: strip symbols
+# -Os: Optimize for size. -ffunction-sections -fdata-sections: breaks function
+# and data into sections so they can be properly gc'd. -s: strip symbols
 set(CMAKE_CXX_FLAGS_RELEASE
     "-Os -ffunction-sections -fdata-sections -s -fno-exceptions -fno-rtti")
 set(CMAKE_CXX_FLAGS_DEBUG "-O0 -g")
@@ -60,8 +66,7 @@ set(CMAKE_CXX_FLAGS_DEBUG "-O0 -g")
 option(
   REGISTER_EXAMPLE_CUSTOM_OP
   "Register whether custom op 1 (my_ops::mul3) or custom op 2 (my_ops::mul4) \
-  or no custom op at all."
-  OFF)
+  or no custom op at all." OFF)
 
 # Option to register quantized ops with quantized kernels. See
 # kernels/quantized/CMakeLists.txt
@@ -86,12 +91,6 @@ endif()
 option(EXECUTORCH_BUILD_XNNPACK
        "Build xnn_executor_runner which depends on XNNPACK" OFF)
 
-set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
-
-if(NOT CMAKE_CXX_STANDARD)
-  set(CMAKE_CXX_STANDARD 17)
-endif()
-
 if(NOT BUCK2)
   set(BUCK2 buck2)
 endif()
@@ -125,11 +124,68 @@ endif()
 message(STATUS "executorch: Using sources file ${EXECUTORCH_SRCS_FILE}")
 include(${EXECUTORCH_SRCS_FILE})
 
+#
+# Modify default options when cross-compiling.
+#
+# The intent is for the EXECUTORCH_BUILD_HOST_TARGETS option to affect the
+# default ON/OFF values of host targets around the tree. This way, a user can
+# disable EXECUTORCH_BUILD_HOST_TARGETS to disable all host targets, and then
+# optionally re-enable some of those targets. Or they could leave
+# EXECUTORCH_BUILD_HOST_TARGETS enabled and then optionally disable any given
+# host target.
+#
+# We can then use various cross-compilation hints to set the default value of
+# EXECUTORCH_BUILD_HOST_TARGETS, which can still be overridden if desired.
+#
+
+# _default_build_host_targets: The default value for the
+# EXECUTORCH_BUILD_HOST_TARGETS option.
+set(_default_build_host_targets ON)
+if(CMAKE_TOOLCHAIN_FILE MATCHES ".*ios\.toolchain\.cmake$")
+  # TODO(dbort): Refactor toolchain-specific matching. Ideally this file would
+  # not know about specific targets, and work with more abstract concepts like
+  # "is cross compiling".
+  set(_default_build_host_targets OFF)
+endif()
+
+# EXECUTORCH_BUILD_HOST_TARGETS: Option to control the building of host-only
+# tools like `flatc`, along with example executables like `executor_runner` and
+# libraries that it uses, like `gflags`. Disabling this can be helpful when
+# cross-compiling, but some required tools that would have been built need to be
+# provided directly (via, for example, FLATC_EXECUTABLE).
+option(EXECUTORCH_BUILD_HOST_TARGETS "Build host-only targets."
+       "${_default_build_host_targets}")
+# Unset this since it's easy to confuse with _default_host_target_option.
+unset(_default_build_host_targets)
+
+# _default_host_target_option: EXECUTORCH_BUILD_* options that guard host tools
+# and libraries should use this as their default value.
+if(EXECUTORCH_BUILD_HOST_TARGETS)
+  set(_default_host_target_option ON)
+else()
+  set(_default_host_target_option OFF)
+endif()
+
 #
 # flatc: Flatbuffer commandline tool to generate .h files from .fbs files
 #
 
-if(NOT FLATC_EXECUTABLE)
+if(FLATC_EXECUTABLE)
+  # A `flatc` is provided, so no need to build another one.
+  set(_default_build_flatc OFF)
+else()
+  set(_default_build_flatc "${_default_host_target_option}")
+endif()
+option(EXECUTORCH_BUILD_FLATC "Build the flatc executable."
+       "${_default_build_flatc}")
+if(EXECUTORCH_BUILD_FLATC)
+  if(FLATC_EXECUTABLE)
+    # We could ignore this, but it could lead to confusion about which `flatc`
+    # is actually being used.
+    message(
+      FATAL_ERROR "May not set both EXECUTORCH_BUILD_FLATC and FLATC_EXECUTABLE"
+    )
+  endif()
   set(FLATC_EXECUTABLE flatc)
   option(FLATBUFFERS_BUILD_FLATC "" ON)
   option(FLATBUFFERS_BUILD_FLATHASH "" OFF)
@@ -138,12 +194,13 @@ if(NOT FLATC_EXECUTABLE)
   option(FLATBUFFERS_INSTALL "" OFF)
   add_subdirectory(third-party/flatbuffers)
 endif()
-
-#
-# gflags: Commandline flag libgrary
-#
-
-add_subdirectory(third-party/gflags)
+if(NOT FLATC_EXECUTABLE)
+  message(
+    FATAL_ERROR
+      "FLATC_EXECUTABLE must be set when EXECUTORCH_BUILD_FLATC is disabled. "
+      "Note that EXECUTORCH_BUILD_FLATC may be disabled implicitly when "
+      "cross-compiling or when EXECUTORCH_BUILD_HOST_TARGETS is disabled.")
+endif()
 
 #
 # program_schema: Generated .h files from schema/*.fbs inputs
@@ -175,27 +232,42 @@ endif()
 # operators necessary for the models that will run.
 #
 add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/kernels/portable)
-set(_libs executorch portable_ops_lib gflags)
 
-# Generate custom_ops_lib based on REGISTER_EXAMPLE_CUSTOM_OP
-if(REGISTER_EXAMPLE_CUSTOM_OP EQUAL 1 OR REGISTER_EXAMPLE_CUSTOM_OP EQUAL 2)
-  add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/examples/custom_ops)
-  list(APPEND _libs custom_ops_lib)
+#
+# gflags: Commandline flag host library.
+#
+option(EXECUTORCH_BUILD_GFLAGS "Build the gflags library."
+       "${_default_host_target_option}")
+if(EXECUTORCH_BUILD_GFLAGS)
+  add_subdirectory(third-party/gflags)
 endif()
 
-# Generate lib to register quantized ops
-if(REGISTER_QUANTIZED_OPS)
-  add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/kernels/quantized)
-  list(APPEND _libs quantized_ops_lib)
-endif()
+#
+# executor_runner: Host tool that demonstrates program execution.
+#
+option(EXECUTORCH_BUILD_EXECUTOR_RUNNER "Build the executor_runner executable"
+       "${_default_host_target_option}")
+if(EXECUTORCH_BUILD_EXECUTOR_RUNNER)
+  # Baseline libraries that executor_runner will link against.
+  set(_executor_runner_libs executorch portable_ops_lib gflags)
+
+  # Generate custom_ops_lib based on REGISTER_EXAMPLE_CUSTOM_OP
+  if(REGISTER_EXAMPLE_CUSTOM_OP EQUAL 1 OR REGISTER_EXAMPLE_CUSTOM_OP EQUAL 2)
+    add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/examples/custom_ops)
+    list(APPEND _executor_runner_libs custom_ops_lib)
+  endif()
+
+  # Generate lib to register quantized ops
+  if(REGISTER_QUANTIZED_OPS)
+    add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/kernels/quantized)
+    list(APPEND _executor_runner_libs quantized_ops_lib)
+  endif()
 
-# ios can only build library but not binary
-if(NOT CMAKE_TOOLCHAIN_FILE MATCHES ".*ios\.toolchain\.cmake$")
   add_executable(executor_runner ${_executor_runner__srcs})
   if(CMAKE_BUILD_TYPE EQUAL "RELEASE")
     target_link_options(executor_runner PRIVATE "LINKER:--gc-sections")
   endif()
-  target_link_libraries(executor_runner ${_libs})
+  target_link_libraries(executor_runner ${_executor_runner_libs})
   target_compile_options(executor_runner PUBLIC ${_common_compile_options})
 endif()
 
diff --git a/backends/xnnpack/CMakeLists.txt b/backends/xnnpack/CMakeLists.txt
@@ -62,7 +62,7 @@ target_include_directories(
   xnnpack_schema INTERFACE ${_xnnpack_schema__include_dir}
                            ${EXECUTORCH_ROOT}/third-party/flatbuffers/include)
 
-set(xnn_executor_runner_libs ${_libs} xnnpack_schema)
+set(xnn_executor_runner_libs ${_executor_runner_libs} xnnpack_schema)
 
 list(TRANSFORM _dynamic_quant_utils__srcs PREPEND "${EXECUTORCH_ROOT}/")
 add_library(dynamic_quant_utils ${_dynamic_quant_utils__srcs})
diff --git a/build/Utils.cmake b/build/Utils.cmake
@@ -4,28 +4,40 @@
 # This source code is licensed under the BSD-style license found in the
 # LICENSE file in the root directory of this source tree.
 
+#
 # This file is intended to have helper functions to keep the CMakeLists.txt
 # concise. If there are any helper function can be re-used, it's recommented to
 # add them here.
+#
+# ### Editing this file ###
+#
+# This file should be formatted with
+# ~~~
+# cmake-format --first-comment-is-literal=True Utils.cmake
+# ~~~
+# It should also be cmake-lint clean.
+#
 
-# Public function to print summary for all configurations. For new variable,
+# Public function to print summary for all configurations. For new variables,
 # it's recommended to add them here.
 function(executorch_print_configuration_summary)
   message(STATUS "")
   message(STATUS "******** Summary ********")
-  message(STATUS "  BUCK                          : ${BUCK2}")
   message(STATUS "  CMAKE_BUILD_TYPE              : ${CMAKE_BUILD_TYPE}")
   message(STATUS "  CMAKE_CXX_STANDARD            : ${CMAKE_CXX_STANDARD}")
   message(STATUS "  CMAKE_CXX_COMPILER_ID         : ${CMAKE_CXX_COMPILER_ID}")
   message(STATUS "  CMAKE_TOOLCHAIN_FILE          : ${CMAKE_TOOLCHAIN_FILE}")
+  message(STATUS "  BUCK2                         : ${BUCK2}")
   message(STATUS "  PYTHON_EXECUTABLE             : ${PYTHON_EXECUTABLE}")
   message(STATUS "  FLATC_EXECUTABLE              : ${FLATC_EXECUTABLE}")
-  message(STATUS "  FLATBUFFERS_BUILD_FLATC       : ${FLATBUFFERS_BUILD_FLATC}")
   message(
-    STATUS "  FLATBUFFERS_BUILD_FLATHASH    : ${FLATBUFFERS_BUILD_FLATHASH}")
+    STATUS "  EXECUTORCH_BUILD_HOST_TARGETS : ${EXECUTORCH_BUILD_HOST_TARGETS}")
+  message(STATUS "  EXECUTORCH_BUILD_FLATC        : ${EXECUTORCH_BUILD_FLATC}")
+  message(STATUS "  EXECUTORCH_BUILD_GFLAGS       : ${EXECUTORCH_BUILD_GFLAGS}")
   message(
-    STATUS "  FLATBUFFERS_BUILD_FLATLIB     : ${FLATBUFFERS_BUILD_FLATLIB}")
-  message(STATUS "  FLATBUFFERS_BUILD_TESTS       : ${FLATBUFFERS_BUILD_TESTS}")
+    STATUS
+      "  EXECUTORCH_BUILD_EXECUTOR_RUNNER : ${EXECUTORCH_BUILD_EXECUTOR_RUNNER}"
+  )
   message(
     STATUS "  REGISTER_EXAMPLE_CUSTOM_OPS   : ${REGISTER_EXAMPLE_CUSTOM_OPS}")
 endfunction()
@@ -37,24 +49,20 @@ function(kernel_link_options target_name)
   # target_link_options(${target_name} INTERFACE
   # "$<LINK_LIBRARY:WHOLE_ARCHIVE,target_name>")
   target_link_options(
-    ${target_name}
-    INTERFACE
-    "SHELL:LINKER:--whole-archive \
+    ${target_name} INTERFACE "SHELL:LINKER:--whole-archive \
     $<TARGET_FILE:${target_name}> \
-    LINKER:--no-whole-archive"
-  )
+    LINKER:--no-whole-archive")
 endfunction()
 
+# Same as kernel_link_options but it's for MacOS linker
 function(macos_kernel_link_options target_name)
-  target_link_options(
-    ${target_name} INTERFACE
-    # Same as kernel_link_options but it's for MacOS linker
-    "SHELL:LINKER:-force_load,$<TARGET_FILE:${target_name}>")
+  target_link_options(${target_name} INTERFACE
+                      "SHELL:LINKER:-force_load,$<TARGET_FILE:${target_name}>")
 endfunction()
 
+# Ensure that the load-time constructor functions run. By default, the linker
+# would remove them since there are no other references to them.
 function(target_link_options_shared_lib target_name)
-  # Ensure that the load-time constructor functions run. By default, the linker
-  # would remove them since there are no other references to them.
   if(APPLE)
     macos_kernel_link_options(${target_name})
   else()
@@ -65,13 +73,15 @@ endfunction()
 # Extract source files based on toml config. This is useful to keep buck2 and
 # cmake aligned.
 function(extract_sources sources_file)
-  if(NOT EXECUTORCH_ROOT)
-    set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR})
+  if(EXECUTORCH_ROOT)
+    set(executorch_root ${EXECUTORCH_ROOT})
+  else()
+    set(executorch_root ${CMAKE_CURRENT_SOURCE_DIR})
   endif()
   execute_process(
     COMMAND
-      ${PYTHON_EXECUTABLE} ${EXECUTORCH_ROOT}/build/extract_sources.py
-      --buck2=${BUCK2} --config=${EXECUTORCH_ROOT}/build/cmake_deps.toml
+      ${PYTHON_EXECUTABLE} ${executorch_root}/build/extract_sources.py
+      --buck2=${BUCK2} --config=${executorch_root}/build/cmake_deps.toml
       --out=${sources_file}
     OUTPUT_VARIABLE gen_srcs_output
     ERROR_VARIABLE gen_srcs_error
