[RFC] Fetch gflags dynamically

.gitignore

@@ -21,6 +21,9 @@ ethos-u-scratch/
 executorch.egg-info
 pip-out/
 
+# Third-party libraries, symlink'ed to FetchContent source directories
+third-party/gflags
+
 # Any exported models and profiling outputs
 *.bin
 *.model

.gitmodules

@@ -40,9 +40,6 @@
 [submodule "third-party/flatcc"]
 	path = third-party/flatcc
 	url = https://github.com/dvidelabs/flatcc.git
-[submodule "third-party/gflags"]
-	path = third-party/gflags
-	url = https://github.com/gflags/gflags.git
 [submodule "third-party/googletest"]
 	path = third-party/googletest
 	url = https://github.com/google/googletest.git

CMakeLists.txt

@@ -52,8 +52,10 @@ project(executorch)
 
 include(${PROJECT_SOURCE_DIR}/tools/cmake/common/preset.cmake)
 include(${PROJECT_SOURCE_DIR}/tools/cmake/Utils.cmake)
+include(${PROJECT_SOURCE_DIR}/tools/cmake/FetchContent.cmake)
 include(CMakeDependentOption)
 include(ExternalProject)
+include(FetchContent)
 
 if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 17)
@@ -456,14 +458,6 @@ endif()
 
 add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/configurations)
 
-#
-# gflags: Commandline flag host library.
-#
-
-if(EXECUTORCH_BUILD_GFLAGS)
-  add_subdirectory(third-party/gflags)
-endif()
-
 # Install `executorch` library as well as `executorch-config.cmake` under
 # ${CMAKE_INSTALL_PREFIX}/
 install(

backends/apple/coreml/scripts/build_tests.sh

@@ -33,8 +33,7 @@ cmake "$EXECUTORCH_ROOT_PATH" -B"$CMAKE_EXECUTORCH_BUILD_DIR_PATH" \
 -DPLATFORM=MAC_UNIVERSAL \
 -DDEPLOYMENT_TARGET=13.0 \
 -DEXECUTORCH_BUILD_EXECUTOR_RUNNER=OFF \
--DEXECUTORCH_BUILD_XNNPACK=OFF \
--DEXECUTORCH_BUILD_GFLAGS=OFF
+-DEXECUTORCH_BUILD_XNNPACK=OFF
 
 cmake --build "$CMAKE_EXECUTORCH_BUILD_DIR_PATH"  -j9 -t executorch
 

backends/cadence/build_cadence_fusionG3.sh

@@ -50,7 +50,6 @@ if $STEPWISE_BUILD; then
         -DEXECUTORCH_BUILD_KERNELS_CUSTOM=OFF \
         -DPYTHON_EXECUTABLE=python3 \
         -DEXECUTORCH_FUSION_G3_OPT=ON \
-        -DEXECUTORCH_BUILD_GFLAGS=ON \
         -DHAVE_FNMATCH_H=OFF \
         -Bcmake-out/backends/cadence \
         backends/cadence

backends/cadence/build_cadence_hifi4.sh

@@ -49,7 +49,6 @@ if $STEPWISE_BUILD; then
         -DEXECUTORCH_BUILD_KERNELS_CUSTOM=OFF \
         -DPYTHON_EXECUTABLE=python3 \
         -DEXECUTORCH_NNLIB_OPT=ON \
-        -DEXECUTORCH_BUILD_GFLAGS=ON \
         -DHAVE_FNMATCH_H=OFF \
         -Bcmake-out/backends/cadence \
         backends/cadence

examples/models/llama/CMakeLists.txt

@@ -47,6 +47,7 @@ set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../../..)
 set(TORCH_ROOT ${EXECUTORCH_ROOT}/third-party/pytorch)
 
 include(${EXECUTORCH_ROOT}/tools/cmake/Utils.cmake)
+include(${EXECUTORCH_ROOT}/tools/cmake/FetchContent.cmake)
 
 if(NOT PYTHON_EXECUTABLE)
   resolve_python_executable()
@@ -68,10 +69,8 @@ set(_common_compile_options -Wno-deprecated-declarations -fPIC)
 # Let files say "include <executorch/path/to/header.h>".
 set(_common_include_directories ${EXECUTORCH_ROOT}/..)
 
-# For some reason android build is not able to find where gflags is and hence
-# cannot find corresponding .cmake file
-set(gflags_DIR ${CMAKE_CURRENT_BINARY_DIR}/../../../third-party/gflags)
-find_package(gflags REQUIRED)
+# Fetch gflags
+FetchContent_gflags()
 
 #
 # llama_main: test binary to run llama, with tokenizer and sampler integrated

examples/models/llava/CMakeLists.txt

@@ -45,6 +45,7 @@ endif()
 set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../../..)
 
 include(${EXECUTORCH_ROOT}/tools/cmake/Utils.cmake)
+include(${EXECUTORCH_ROOT}/tools/cmake/FetchContent.cmake)
 
 if(NOT PYTHON_EXECUTABLE)
   resolve_python_executable()
@@ -66,10 +67,8 @@ set(_common_compile_options -Wno-deprecated-declarations -fPIC)
 # Let files say "include <executorch/path/to/header.h>".
 set(_common_include_directories ${EXECUTORCH_ROOT}/..)
 
-# For some reason android build is not able to find where gflags is and hence
-# cannot find corresponding .cmake file
-set(gflags_DIR ${CMAKE_CURRENT_BINARY_DIR}/../../../third-party/gflags)
-find_package(gflags REQUIRED)
+# Fetch gflags
+FetchContent_gflags()
 
 #
 # llava_main: test binary to run llava, with tokenizer and sampler integrated

examples/portable/custom_ops/CMakeLists.txt

@@ -29,6 +29,7 @@ endif()
 
 include(${EXECUTORCH_ROOT}/tools/cmake/Utils.cmake)
 include(${EXECUTORCH_ROOT}/tools/cmake/Codegen.cmake)
+include(${EXECUTORCH_ROOT}/tools/cmake/FetchContent.cmake)
 
 if(NOT PYTHON_EXECUTABLE)
   resolve_python_executable()
@@ -40,9 +41,7 @@ set(_common_compile_options -Wno-deprecated-declarations -fPIC)
 set(_common_include_directories ${EXECUTORCH_ROOT}/..)
 
 find_package(executorch CONFIG REQUIRED)
-find_package(
-  gflags REQUIRED PATHS ${CMAKE_CURRENT_BINARY_DIR}/../../../third-party
-)
+FetchContent_gflags()
 
 target_include_directories(executorch INTERFACE ${_common_include_directories})
 

examples/qualcomm/CMakeLists.txt

@@ -30,7 +30,6 @@ endif()
 # etdump, bundled_program.
 find_package(executorch CONFIG REQUIRED)
 target_compile_options(executorch INTERFACE -DET_EVENT_TRACER_ENABLED)
-find_package(gflags REQUIRED)
 
 set(_common_compile_options -Wno-deprecated-declarations -fPIC)
 

examples/selective_build/CMakeLists.txt

@@ -23,6 +23,7 @@ set(TORCH_ROOT ${EXECUTORCH_ROOT}/third-party/pytorch)
 
 include(${EXECUTORCH_ROOT}/tools/cmake/Utils.cmake)
 include(${EXECUTORCH_ROOT}/tools/cmake/Codegen.cmake)
+include(${EXECUTORCH_ROOT}/tools/cmake/FetchContent.cmake)
 
 if(NOT PYTHON_EXECUTABLE)
   resolve_python_executable()
@@ -39,9 +40,7 @@ set(_common_compile_options -Wno-deprecated-declarations -fPIC)
 set(_common_include_directories ${EXECUTORCH_ROOT}/..)
 
 find_package(executorch CONFIG REQUIRED)
-find_package(
-  gflags REQUIRED PATHS ${CMAKE_CURRENT_BINARY_DIR}/../../third-party
-)
+FetchContent_gflags()
 
 target_include_directories(executorch_core INTERFACE ${_common_include_directories})
 

extension/training/CMakeLists.txt

@@ -31,6 +31,7 @@ target_link_libraries(extension_training executorch_core kernels_util_all_deps
 
 list(TRANSFORM _train_xor__srcs PREPEND "${EXECUTORCH_ROOT}/")
 add_executable(train_xor ${_train_xor__srcs})
+
 target_include_directories(
   train_xor PUBLIC ${_common_include_directories}
 )

third-party/CMakeLists.txt

@@ -14,6 +14,13 @@ if(BUILD_TESTING)
   add_subdirectory(googletest)
 endif()
 
+FetchContent_gflags()
+# Create a symlink from the gflags source directory to third-party/gflags
+message(STATUS "gflags source dir: ${gflags_SOURCE_DIR}")
+execute_process(
+  COMMAND ${CMAKE_COMMAND} -E create_symlink "${gflags_SOURCE_DIR}" "${CMAKE_CURRENT_SOURCE_DIR}/gflags"
+)
+
 # MARK: - flatbuffers
 
 if(WIN32)

tools/cmake/FetchContent.cmake

@@ -0,0 +1,19 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# FetchContent gflags and make available at CMake configure time.
+# Make the content available at configure time so that BUCK can use it.
+include(FetchContent)
+
+function(FetchContent_gflags)
+  FetchContent_Declare(
+    gflags
+    GIT_REPOSITORY https://github.com/gflags/gflags.git
+    GIT_TAG v2.2.2
+  )
+  set(GFLAGS_INTTYPES_FORMAT C99)
+  FetchContent_MakeAvailable(gflags)
+endfunction()

tools/cmake/preset/default.cmake

@@ -209,11 +209,6 @@ define_overridable_option(
   "Build the Cortex-M backend"
   BOOL OFF
 )
-define_overridable_option(
-  EXECUTORCH_BUILD_GFLAGS
-  "Build the gflags library."
-  BOOL ON
-)
 define_overridable_option(
   EXECUTORCH_COREML_BUILD_EXECUTOR_RUNNER
   "Build CoreML executor runner."