Merge pull request #1973 from Xreki/cmake_protobuf

Add cross-compiling toolchain files for Android and Raspberry Pi.

CMakeLists.txt

@@ -12,17 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License
 
+cmake_minimum_required(VERSION 3.0)
+
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
 set(PROJ_ROOT ${CMAKE_CURRENT_SOURCE_DIR})
 
 include(system)
 
-if(ANDROID)
-    cmake_minimum_required(VERSION 3.7)
-else()
-    cmake_minimum_required(VERSION 3.0)
-endif()
-
 project(paddle CXX C)
 
 find_package(Sphinx)

cmake/cross_compiling/android.cmake

+# Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# 
+# http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This is a toolchain file for cross-compiling for Android, and the
+# configuration refers to the open-source resposity:
+#     https://github.com/taka-no-me/android-cmake
+# Most of the variables are compatible with that used in
+#     https://developer.android.com/ndk/guides/cmake.html
+# The supported variables are listed belows:
+# 
+# ANDROID_STANDALONE_TOOLCHAIN
+# ANDROID_ABI
+# ANDROID_NATIVE_API_LEVEL
+# ANDROID_ARM_MODE
+# ANDROID_ARM_NEON
+#
+# For CMake >= 3.7.0, all the settings will be delivered to CMake system
+# variables to let CMake do the cross-compiling configurations itself.
+# More detail of cross-compiling settings
+#     https://cmake.org/cmake/help/v3.7/manual/cmake-toolchains.7.html
+
+IF(NOT ANDROID)
+    return()
+ENDIF()
+
+# check the exist of android standalone toolchain
+IF(NOT DEFINED ANDROID_STANDALONE_TOOLCHAIN)
+    SET(ANDROID_STANDALONE_TOOLCHAIN $ENV{ANDROID_STANDALONE_TOOLCHAIN}
+        CACHE PATH "Folder holds the standalone toolchain of Android NDK")
+ENDIF()
+IF(NOT ANDROID_STANDALONE_TOOLCHAIN)
+    MESSAGE(WARNING "It is recommended to set ANDROID_STANDALONE_TOOLCHAIN to "
+            "use a standalone toolchain.\n"
+            "To cross-compile for Android, you need to:\n"
+            "1. Download an Android NDK from"
+            " https://developer.android.com/ndk/downloads/index.html\n"
+            "2. Setup a standalone toolchain"
+            "https://developer.android.google.cn/ndk/guides/standalone_toolchain.html?hl=zh-cn\n")
+ENDIF()
+
+IF(NOT DEFINED CMAKE_SYSTEM_VERSION AND ANDROID_NATIVE_API_LEVEL)
+    IF(ANDROID_NATIVE_API_LEVEL MATCHES "^android-[0-9]+$")
+        STRING(REPLACE "android-" "" CMAKE_SYSTEM_VERSION "${CMAKE_MATCH_0}")
+    ELSEIF(ANDROID_NATIVE_API_LEVEL MATCHES "^[0-9]+$")
+        SET(CMAKE_SYSTEM_VERSION ${ANDROID_NATIVE_API_LEVEL})
+    ENDIF()
+ENDIF()
+
+IF(NOT DEFINED ANDROID_ABI)
+    SET(ANDROID_ABI "armeabi-v7a")
+ENDIF()
+
+IF(NOT DEFINED ANDROID_ARM_MODE)
+    SET(ANDROID_ARM_MODE ON)
+ENDIF()
+IF(ANDROID_ARM_MODE)
+    SET(ANDROID_ARM_MODE_NAME "arm")
+ELSE(ANDROID_ARM_MODE)
+    SET(ANDROID_ARM_MODE_NAME "thumb")
+ENDIF(ANDROID_ARM_MODE)
+
+IF(NOT DEFINED ANDROID_ARM_NEON)
+    SET(ANDROID_ARM_NEON ON)
+ENDIF()
+
+IF("${CMAKE_VERSION}" VERSION_LESS "3.7.0")
+    IF("${CMAKE_VERSION}" VERSION_LESS "3.1.0")
+        SET(CMAKE_SYSTEM_NAME "Linux")
+    ENDIF()
+    MESSAGE(WARNING "It is recommended to use CMake >= 3.7.0 (current version: "
+            "${CMAKE_VERSION}), when cross-compiling for Android.")
+
+    IF(ANDROID_STANDALONE_TOOLCHAIN)
+        SET(CMAKE_SYSROOT "${ANDROID_STANDALONE_TOOLCHAIN}/sysroot")
+
+        IF(NOT CMAKE_SYSTEM_VERSION)
+            SET(ANDROID_STANDALONE_TOOLCHAIN_API "")
+            SET(ANDROID_API_LEVEL_H_REGEX "^[\t ]*#[\t ]*define[\t ]+__ANDROID_API__[\t ]+([0-9]+)")
+            FILE(STRINGS "${ANDROID_STANDALONE_TOOLCHAIN}/sysroot/usr/include/android/api-level.h"
+                ANDROID_API_LEVEL_H_CONTENT REGEX "${ANDROID_API_LEVEL_H_REGEX}")
+            IF(ANDROID_API_LEVEL_H_CONTENT MATCHES "${ANDROID_API_LEVEL_H_REGEX}")
+                SET(ANDROID_STANDALONE_TOOLCHAIN_API "${CMAKE_MATCH_1}")
+            ENDIF()
+            SET(CMAKE_SYSTEM_VERSION ${ANDROID_STANDALONE_TOOLCHAIN_API})
+        ENDIF()
+
+        # Toolchain
+        SET(ANDROID_TOOLCHAIN "gcc")
+        SET(ANDROID_TOOLCHAIN_ROOT ${ANDROID_STANDALONE_TOOLCHAIN})
+        IF(ANDROID_ABI MATCHES "^armeabi(-v7a)?$")
+            SET(ANDROID_TOOLCHAIN_NAME arm-linux-androideabi)
+            IF(ANDROID_ABI STREQUAL "armeabi")
+                SET(CMAKE_SYSTEM_PROCESSOR armv5te)
+            ELSEIF(ANDROID_ABI STREQUAL "armeabi-v7a")
+                SET(CMAKE_SYSTEM_PROCESSOR armv7-a)
+            ENDIF()
+        ENDIF()
+        SET(ANDROID_TOOLCHAIN_PREFIX "${ANDROID_TOOLCHAIN_ROOT}/bin/${ANDROID_TOOLCHAIN_NAME}-")
+    ENDIF()
+
+    # C compiler
+    IF(NOT CMAKE_C_COMPILER)
+        SET(ANDROID_C_COMPILER "${ANDROID_TOOLCHAIN_PREFIX}gcc")
+    ELSE()
+        GET_FILENAME_COMPONENT(ANDROID_C_COMPILER ${CMAKE_C_COMPILER} PROGRAM)
+    ENDIF()
+    IF(NOT EXISTS ${ANDROID_C_COMPILER})
+        MESSAGE(FATAL_ERROR "Cannot find C compiler: ${ANDROID_C_COMPILER}")
+    ENDIF()
+
+    # CXX compiler
+    IF(NOT CMAKE_CXX_COMPILER)
+        SET(ANDROID_CXX_COMPILER "${ANDROID_TOOLCHAIN_PREFIX}g++")
+    ELSE()
+        GET_FILENAME_COMPONENT(ANDROID_CXX_COMPILER ${CMAKE_CXX_COMPILER} PROGRAM)
+    ENDIF()
+    IF(NOT EXISTS ${ANDROID_CXX_COMPILER})
+        MESSAGE(FATAL_ERROR "Cannot find CXX compiler: ${ANDROID_CXX_COMPILER}")
+    ENDIF()
+
+    SET(CMAKE_C_COMPILER ${ANDROID_C_COMPILER} CACHE PATH "C compiler" FORCE)
+    SET(CMAKE_CXX_COMPILER ${ANDROID_CXX_COMPILER} CACHE PATH "CXX compiler" FORCE)
+
+    # Toolchain and ABI specific flags.
+    SET(ANDROID_COMPILER_FLAGS "-ffunction-sections -fdata-sections -finline-limit=64")
+    SET(ANDROID_LINKER_FLAGS "-Wl,--gc-sections")
+
+    IF(ANDROID_ABI STREQUAL "armeabi")
+        LIST(APPEND ANDROID_COMPILER_FLAGS
+             -march=armv5te
+             -mtune=xscale
+             -msoft-float)
+    ENDIF()
+    IF(ANDROID_ABI STREQUAL "armeabi-v7a")
+        LIST(APPEND ANDROID_COMPILER_FLAGS
+             -march=armv7-a
+             -mfloat-abi=softfp)
+        IF(ANDROID_ARM_NEON)
+            LIST(APPEND ANDROID_COMPILER_FLAGS -mfpu=neon)
+        ELSE()
+            LIST(APPEND ANDROID_COMPILER_FLAGS -mfpu=vfpv3-d16)
+        ENDIF()
+        LIST(APPEND ANDROID_LINKER_FLAGS -Wl,--fix-cortex-a8)
+    ENDIF()
+
+    IF(ANDROID_ABI MATCHES "^armeabi(-v7a)?$")
+        IF(ANDROID_ARM_MODE)
+            LIST(APPEND ANDROID_COMPILER_FLAGS -marm)
+        ELSE()
+            LIST(APPEND ANDROID_COMPILER_FLAGS -mthumb)
+        ENDIF()
+    ENDIF()
+
+    STRING(REPLACE ";" " " ANDROID_COMPILER_FLAGS "${ANDROID_COMPILER_FLAGS}")
+    STRING(REPLACE ";" " " ANDROID_LINKER_FLAGS "${ANDROID_LINKER_FLAGS}")
+
+    SET(CMAKE_C_FLAGS "${ANDROID_COMPILER_FLAGS} ${CMAKE_C_FLAGS}"
+        CACHE STRING "C flags")
+    SET(CMAKE_CXX_FLAGS "${ANDROID_COMPILER_FLAGS} ${CMAKE_CXX_FLAGS}"
+        CACHE STRING "CXX flags")
+    SET(CMAKE_SHARED_LINKER_FLAGS "${ANDROID_LINKER_FLAGS} ${CMAKE_SHARED_LINKER_FLAGS}"
+        CACHE STRING "shared linker flags")
+
+    SET(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
+    SET(CMAKE_EXE_LINKER_FLAGS "-pie -fPIE ${ANDROID_LINKER_FLAGS} ${CMAKE_EXE_LINKER_FLAGS}"
+        CACHE STRING "executable linker flags")
+
+    MESSAGE(STATUS "Android: Targeting API '${CMAKE_SYSTEM_VERSION}' "
+            "with architecture '${ANDROID_ARM_MODE_NAME}', "
+            "ABI '${ANDROID_ABI}', and processor '${CMAKE_SYSTEM_PROCESSOR}'")
+    MESSAGE(STATUS "System CMAKE_C_FLAGS: " ${CMAKE_C_FLAGS})
+    MESSAGE(STATUS "System CMAKE_CXX_FLAGS: " ${CMAKE_CXX_FLAGS})
+ELSE()
+    IF(ANDROID_STANDALONE_TOOLCHAIN)
+        SET(CMAKE_ANDROID_STANDALONE_TOOLCHAIN ${ANDROID_STANDALONE_TOOLCHAIN})
+    ENDIF()
+    SET(CMAKE_ANDROID_ARCH_ABI ${ANDROID_ABI})
+    SET(CMAKE_ANDROID_ARM_MODE ${ANDROID_ARM_MODE})
+    SET(CMAKE_ANDROID_ARM_NEON ${ANDROID_ARM_NEON})
+ENDIF()

cmake/cross_compiling/host.cmake

+# Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# 
+# http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# find host C compiler
+IF(HOST_C_COMPILER)
+    SET(HOST_C_COMPILER_NAME ${HOST_C_COMPILER})
+ELSEIF(NOT $ENV{CC} STREQUAL "")
+    SET(HOST_C_COMPILER_NAME $ENV{CC})
+ELSE()
+    SET(HOST_C_COMPILER_NAME cc)
+ENDIF()
+
+GET_FILENAME_COMPONENT(HOST_C_COMPILER_PATH ${HOST_C_COMPILER_NAME} PROGRAM)
+IF(NOT HOST_C_COMPILER_PATH OR NOT EXISTS ${HOST_C_COMPILER_PATH})
+    MESSAGE(FATAL_ERROR "Cannot find host C compiler, set host C compiler:\n"
+            "\tcmake .. -DHOST_C_COMPILER=...")
+ENDIF()
+
+# find host CXX compiler
+IF(HOST_CXX_COMPILER)
+    SET(HOST_CXX_COMPILER_NAME ${HOST_CXX_COMPILER})
+ELSEIF(NOT $ENV{CXX} STREQUAL "")
+    SET(HOST_CXX_COMPILER_NAME $ENV{CXX})
+ELSE()
+    SET(HOST_CXX_COMPILER_NAME c++)
+ENDIF()
+
+GET_FILENAME_COMPONENT(HOST_CXX_COMPILER_PATH ${HOST_CXX_COMPILER_NAME} PROGRAM)
+IF(NOT HOST_CXX_COMPILER_PATH OR NOT EXISTS ${HOST_CXX_COMPILER_PATH})
+    MESSAGE(FATAL_ERROR "Cannot find host CXX compiler, set host CXX compiler:\n"
+            "\tcmake .. -DHOST_CXX_COMPILER=...")
+ENDIF()
+
+SET(HOST_C_COMPILER ${HOST_C_COMPILER_PATH} CACHE PATH "Host C compiler")
+SET(HOST_CXX_COMPILER ${HOST_CXX_COMPILER_PATH} CACHE PATH "Host CXX compiler")
+
+MESSAGE(STATUS "Found host C compiler: " ${HOST_C_COMPILER})
+MESSAGE(STATUS "Found host CXX compiler: " ${HOST_CXX_COMPILER})

cmake/cross_compiling/raspberry_pi.cmake

+# Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# 
+# http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This is a toolchain file for cross-compiling for Raspberry Pi.
+# The supported variables are listed belows:
+#
+# RPI_TOOLCHAIN
+# RPI_ARM_NEON
+#
+# Also you can set CMAKE_C/CXX_COMPILER yourself, through cmake arguments.
+
+IF(NOT RPI)
+    return()
+ENDIF()
+ 
+SET(CMAKE_SYSTEM_NAME Linux)
+SET(CMAKE_SYSTEM_VERSION 1)
+SET(CMAKE_SYSTEM_PROCESSOR arm)
+
+# check the exist of raspberry pi toolchain
+IF(NOT DEFINED RPI_TOOLCHAIN)
+    SET(RPI_TOOLCHAIN $ENV{RPI_TOOLCHAIN}
+        CACHE PATH "Folder holds the toolchain of Raspberr Pi")
+ENDIF()
+IF(NOT RPI_TOOLCHAIN)
+    MESSAGE(WARNING "It is recommended to set RPI_TOOLCHAIN to use toolchain.\n"
+            "To cross-compile for Raspberry Pi, you need to download the tools using:\n"
+            " git clone https://github.com/raspberrypi/tools\n")
+ENDIF()
+
+IF(NOT DEFINED RPI_ARM_NEON)
+    SET(RPI_ARM_NEON ON)
+ENDIF()
+
+IF(RPI_TOOLCHAIN)
+    SET(RPI_TOOLCHAIN_ROOT ${RPI_TOOLCHAIN})
+    IF(RPI_TOOLCHAIN_ROOT MATCHES "gcc-linaro-arm-linux-gnueabihf-raspbian(-x64)?$")
+        # gcc-linaro-arm-linux-gnueabihf-raspbian
+        # gcc-linaro-arm-linux-gnueabihf-raspbian-x64
+        SET(RPI_TOOLCHAIN_NAME arm-linux-gnueabihf)
+    ENDIF()
+    SET(RPI_TOOLCHAIN_PREFIX "${RPI_TOOLCHAIN_ROOT}/bin/${RPI_TOOLCHAIN_NAME}-")
+ENDIF()
+
+# C compiler
+IF(NOT CMAKE_C_COMPILER)
+    SET(RPI_C_COMPILER "${RPI_TOOLCHAIN_PREFIX}gcc")
+ELSE()
+    GET_FILENAME_COMPONENT(RPI_C_COMPILER ${CMAKE_C_COMPILER} PROGRAM)
+ENDIF()
+IF(NOT EXISTS ${RPI_C_COMPILER})
+    MESSAGE(FATAL_ERROR "Cannot find C compiler: ${RPI_C_COMPILER}")
+ENDIF()
+
+# CXX compiler
+IF(NOT CMAKE_CXX_COMPILER)
+    SET(RPI_CXX_COMPILER "${RPI_TOOLCHAIN_PREFIX}g++")
+ELSE()
+    GET_FILENAME_COMPONENT(RPI_CXX_COMPILER ${CMAKE_CXX_COMPILER} PROGRAM)
+ENDIF()
+IF(NOT EXISTS ${RPI_CXX_COMPILER})
+    MESSAGE(FATAL_ERROR "Cannot find CXX compiler: ${RPI_CXX_COMPILER}")
+ENDIF()
+
+SET(CMAKE_C_COMPILER ${RPI_C_COMPILER} CACHE PATH "C compiler" FORCE)
+SET(CMAKE_CXX_COMPILER ${RPI_CXX_COMPILER} CACHE PATH "CXX compiler" FORCE)
+
+IF(RPI_ARM_NEON)
+    SET(RPI_C_FLAGS "${RPI_C_FLAGS} -mfpu=neon")
+ENDIF()
+
+SET(CMAKE_C_FLAGS "${RPI_C_FLAGS} ${CMAKE_C_FLAGS}" CACHE STRING "C flags")
+SET(CMAKE_CXX_FLAGS "${RPI_C_FLAGS} ${CMAKE_CXX_FLAGS}" CACHE STRING "CXX flags")

cmake/external/openblas.cmake

@@ -21,21 +21,34 @@ IF(NOT ${CBLAS_FOUND})
     SET(CBLAS_INSTALL_DIR ${THIRD_PARTY_PATH}/install/openblas)
     SET(CBLAS_INC_DIR "${CBLAS_INSTALL_DIR}/include" CACHE PATH "openblas include directory." FORCE)
 
-    IF(WIN32)
-        SET(CBLAS_LIBRARIES "${CBLAS_INSTALL_DIR}/lib/openblas.lib" CACHE FILEPATH "openblas library." FORCE)
-    ELSE(WIN32)
-        SET(CBLAS_LIBRARIES "${CBLAS_INSTALL_DIR}/lib/libopenblas.a" CACHE FILEPATH "openblas library" FORCE)
-    ENDIF(WIN32)
+    SET(CBLAS_LIBRARIES "${CBLAS_INSTALL_DIR}/lib/${LIBRARY_PREFIX}openblas${STATIC_LIBRARY_SUFFIX}"
+        CACHE FILEPATH "openblas library." FORCE)
+
+    SET(COMMON_ARGS CC=${CMAKE_C_COMPILER} NO_SHARED=1 NO_LAPACK=1)
+
+    IF(ANDROID)
+        # arm_soft_fp_abi branch of OpenBLAS to support softfp
+        #   https://github.com/xianyi/OpenBLAS/tree/arm_soft_fp_abi
+        SET(OPENBLAS_COMMIT "b5c96fcfcdc82945502a2303116a64d89985daf5")
+        SET(OPTIONAL_ARGS HOSTCC=${HOST_C_COMPILER} TARGET=ARMV7 ARM_SOFTFP_ABI=1 USE_THREAD=0 libs)
+    ELSEIF(RPI)
+        # use hardfp
+        SET(OPENBLAS_COMMIT "v0.2.19")
+        SET(OPTIONAL_ARGS HOSTCC=${HOST_C_COMPILER} TARGET=ARMV7 USE_THREAD=0 libs)
+    ELSE()
+        SET(OPENBLAS_COMMIT "v0.2.19")
+        SET(OPENBLAS_ARGS DYNAMIC_ARCH=1 libs)
+    ENDIF()
 
     ExternalProject_Add(
         openblas
         ${EXTERNAL_PROJECT_LOG_ARGS}
         GIT_REPOSITORY      https://github.com/xianyi/OpenBLAS.git
-        GIT_TAG             v0.2.19
+        GIT_TAG             ${OPENBLAS_COMMIT}
         PREFIX              ${CBLAS_SOURCES_DIR}
         INSTALL_DIR         ${CBLAS_INSTALL_DIR}
         BUILD_IN_SOURCE     1
-        BUILD_COMMAND       ${CMAKE_MAKE_PROGRAM} FC=${CMAKE_Fortran_COMPILER} CC=${CMAKE_C_COMPILER} HOSTCC=${CMAKE_C_COMPILER} NO_LAPACK=1 DYNAMIC_ARCH=1 NO_SHARED=1 libs netlib
+        BUILD_COMMAND       ${CMAKE_MAKE_PROGRAM} ${COMMON_ARGS} ${OPTIONAL_ARGS}
         INSTALL_COMMAND     ${CMAKE_MAKE_PROGRAM} install NO_SHARED=1 NO_LAPACK=1 PREFIX=<INSTALL_DIR>
         UPDATE_COMMAND      ""
         CONFIGURE_COMMAND   ""
@@ -43,4 +56,5 @@ IF(NOT ${CBLAS_FOUND})
     LIST(APPEND external_project_dependencies openblas)
 ENDIF(NOT ${CBLAS_FOUND})
 
+MESSAGE(STATUS "BLAS library: ${CBLAS_LIBRARIES}")
 INCLUDE_DIRECTORIES(${CBLAS_INC_DIR})

cmake/external/protobuf.cmake

@@ -14,42 +14,42 @@
 
 INCLUDE(ExternalProject)
 
-set(PROTOBUF_VERSION 3.1)
-FIND_PACKAGE(Protobuf ${PROTOBUF_VERSION})
+FUNCTION(build_protobuf TARGET_NAME BUILD_FOR_HOST)
+    SET(PROTOBUF_SOURCES_DIR ${THIRD_PARTY_PATH}/${TARGET_NAME})
+    SET(PROTOBUF_INSTALL_DIR ${THIRD_PARTY_PATH}/install/${TARGET_NAME})
 
-IF(PROTOBUF_FOUND)
-    EXEC_PROGRAM(${PROTOBUF_PROTOC_EXECUTABLE} ARGS --version OUTPUT_VARIABLE PROTOBUF_VERSION)
-    STRING(REGEX MATCH "[0-9]+.[0-9]+" PROTOBUF_VERSION "${PROTOBUF_VERSION}")
-    IF ("${PROTOBUF_VERSION}" VERSION_LESS "3.1.0")
-        SET(PROTOBUF_FOUND OFF)
-    ENDIF()
-ENDIF(PROTOBUF_FOUND)
-
-IF(NOT PROTOBUF_FOUND)
-    SET(PROTOBUF_SOURCES_DIR ${THIRD_PARTY_PATH}/protobuf)
-    SET(PROTOBUF_INSTALL_DIR ${THIRD_PARTY_PATH}/install/protobuf)
-    SET(PROTOBUF_INCLUDE_DIR "${PROTOBUF_INSTALL_DIR}/include" CACHE PATH "protobuf include directory." FORCE)
+    SET(${TARGET_NAME}_INCLUDE_DIR "${PROTOBUF_INSTALL_DIR}/include" PARENT_SCOPE)
+    SET(PROTOBUF_INCLUDE_DIR "${PROTOBUF_INSTALL_DIR}/include" PARENT_SCOPE)
+    SET(${TARGET_NAME}_LITE_LIBRARY
+        "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf-lite${STATIC_LIBRARY_SUFFIX}"
+         PARENT_SCOPE)
+    SET(${TARGET_NAME}_LIBRARY
+        "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf${STATIC_LIBRARY_SUFFIX}"
+         PARENT_SCOPE)
+    SET(${TARGET_NAME}_PROTOC_LIBRARY
+        "${PROTOBUF_INSTALL_DIR}/lib/libprotoc${STATIC_LIBRARY_SUFFIX}"
+         PARENT_SCOPE)
+    SET(${TARGET_NAME}_PROTOC_EXECUTABLE
+        "${PROTOBUF_INSTALL_DIR}/bin/protoc${EXECUTABLE_SUFFIX}"
+         PARENT_SCOPE)
 
-    IF(WIN32)
-        SET(PROTOBUF_LITE_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf-lite.lib" CACHE FILEPATH "protobuf lite library." FORCE)
-        SET(PROTOBUF_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf.lib" CACHE FILEPATH "protobuf library." FORCE)
-        SET(PROTOBUF_PROTOC_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotoc.lib" CACHE FILEPATH "protoc library." FORCE)
-        SET(PROTOBUF_PROTOC_EXECUTABLE "${PROTOBUF_INSTALL_DIR}/bin/protoc.exe" CACHE FILEPATH "protobuf executable." FORCE)
-    ELSE(WIN32)
-        SET(PROTOBUF_LITE_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf-lite.a" CACHE FILEPATH "protobuf lite library." FORCE)
-        SET(PROTOBUF_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotobuf.a" CACHE FILEPATH "protobuf library." FORCE)
-        SET(PROTOBUF_PROTOC_LIBRARY
-            "${PROTOBUF_INSTALL_DIR}/lib/libprotoc.a" CACHE FILEPATH "protoc library." FORCE)
-        SET(PROTOBUF_PROTOC_EXECUTABLE "${PROTOBUF_INSTALL_DIR}/bin/protoc" CACHE FILEPATH "protobuf executable." FORCE)
-    ENDIF(WIN32)
+    SET(OPTIONAL_CACHE_ARGS "")
+    SET(OPTIONAL_ARGS "")
+    IF(BUILD_FOR_HOST)
+        SET(OPTIONAL_ARGS "-Dprotobuf_WITH_ZLIB=OFF")
+    ELSE()
+        SET(OPTIONAL_ARGS
+            "-DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}"
+            "-DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}"
+            "-DCMAKE_CXX_FLAGS=${CMAKE_CXX_FLAGS}"
+            "-DCMAKE_C_FLAGS=${CMAKE_C_FLAGS}"
+            "-Dprotobuf_WITH_ZLIB=ON"
+            "-DZLIB_ROOT:FILEPATH=${ZLIB_ROOT}")
+        SET(OPTIONAL_CACHE_ARGS "-DZLIB_ROOT:STRING=${ZLIB_ROOT}")
+    ENDIF()
 
     ExternalProject_Add(
-        protobuf
+        ${TARGET_NAME}
         ${EXTERNAL_PROJECT_LOG_ARGS}
         PREFIX          ${PROTOBUF_SOURCES_DIR}
         UPDATE_COMMAND  ""
@@ -57,11 +57,9 @@ IF(NOT PROTOBUF_FOUND)
         GIT_REPOSITORY  "https://github.com/google/protobuf.git"
         GIT_TAG         "9f75c5aa851cd877fb0d93ccc31b8567a6706546"
         CONFIGURE_COMMAND
-        ${CMAKE_COMMAND} ${PROTOBUF_SOURCES_DIR}/src/protobuf/cmake
+        ${CMAKE_COMMAND} ${PROTOBUF_SOURCES_DIR}/src/${TARGET_NAME}/cmake
+            ${OPTIONAL_ARGS}
             -Dprotobuf_BUILD_TESTS=OFF
-            -DZLIB_ROOT:FILEPATH=${ZLIB_ROOT}
-            -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
-            -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
             -DCMAKE_POSITION_INDEPENDENT_CODE=ON
             -DCMAKE_BUILD_TYPE=Release
             -DCMAKE_INSTALL_PREFIX=${PROTOBUF_INSTALL_DIR}
@@ -71,10 +69,44 @@ IF(NOT PROTOBUF_FOUND)
             -DCMAKE_BUILD_TYPE:STRING=Release
             -DCMAKE_VERBOSE_MAKEFILE:BOOL=OFF
             -DCMAKE_POSITION_INDEPENDENT_CODE:BOOL=ON
-            -DZLIB_ROOT:STRING=${ZLIB_ROOT}
+            ${OPTIONAL_CACHE_ARGS}
     )
+ENDFUNCTION()
+
+SET(PROTOBUF_VERSION 3.1)
+IF(NOT CMAKE_CROSSCOMPILING)
+    FIND_PACKAGE(Protobuf ${PROTOBUF_VERSION})
 
+    IF(PROTOBUF_FOUND)
+        EXEC_PROGRAM(${PROTOBUF_PROTOC_EXECUTABLE} ARGS --version OUTPUT_VARIABLE PROTOBUF_VERSION)
+        STRING(REGEX MATCH "[0-9]+.[0-9]+" PROTOBUF_VERSION "${PROTOBUF_VERSION}")
+        IF("${PROTOBUF_VERSION}" VERSION_LESS "3.1.0")
+            SET(PROTOBUF_FOUND OFF)
+        ENDIF()
+    ENDIF(PROTOBUF_FOUND)
+ELSE()
+    build_protobuf(protobuf_host TRUE)
+    LIST(APPEND external_project_dependencies protobuf_host)
+
+    SET(PROTOBUF_PROTOC_EXECUTABLE ${protobuf_host_PROTOC_EXECUTABLE}
+        CACHE FILEPATH "protobuf executable." FORCE)
+ENDIF()
+
+IF(NOT PROTOBUF_FOUND)
+    build_protobuf(protobuf FALSE)
     LIST(APPEND external_project_dependencies protobuf)
+
+    SET(PROTOBUF_INCLUDE_DIR ${protobuf_INCLUDE_DIR}
+        CACHE PATH "protobuf include directory." FORCE)
+    IF(NOT CMAKE_CROSSCOMPILING)
+        SET(PROTOBUF_PROTOC_EXECUTABLE ${protobuf_PROTOC_EXECUTABLE}
+            CACHE FILEPATH "protobuf executable." FORCE)
+    ENDIF()
+    SET(PROTOBUF_LITE_LIBRARY ${protobuf_LITE_LIBRARY} CACHE FILEPATH "protobuf lite library." FORCE)
+    SET(PROTOBUF_LIBRARY ${protobuf_LIBRARY} CACHE FILEPATH "protobuf library." FORCE)
+    SET(PROTOBUF_PROTOC_LIBRARY ${protobuf_PROTOC_LIBRARY} CACHE FILEPATH "protoc library." FORCE)
 ENDIF(NOT PROTOBUF_FOUND)
 
+MESSAGE(STATUS "Protobuf protoc executable: ${PROTOBUF_PROTOC_EXECUTABLE}")
+MESSAGE(STATUS "Protobuf library: ${PROTOBUF_LIBRARY}")
 INCLUDE_DIRECTORIES(${PROTOBUF_INCLUDE_DIR})

cmake/system.cmake

@@ -13,9 +13,9 @@
 # limitations under the License.
 
 # Detects the OS and sets appropriate variables.
-# CMAKE_SYSTEM_NAME only give us a coarse-grained name,
-# but the name like centos is necessary in some scenes
-# to distinguish system for customization.
+# CMAKE_SYSTEM_NAME only give us a coarse-grained name of the OS CMake is
+# building for, but the host processor name like centos is necessary
+# in some scenes to distinguish system for customization.
 #
 # for instance, protobuf libs path is <install_dir>/lib64
 # on CentOS, but <install_dir>/lib on other systems.
@@ -72,12 +72,36 @@ MARK_AS_ADVANCED(HOST_SYSTEM CPU_CORES)
 MESSAGE(STATUS "Found Paddle host system: ${HOST_SYSTEM}")
 MESSAGE(STATUS "Found Paddle host system's CPU: ${CPU_CORES} cores")
 
+# configuration for cross-compiling
 IF(DEFINED CMAKE_SYSTEM_NAME)
+    INCLUDE(cross_compiling/host)
     IF(${CMAKE_SYSTEM_NAME} STREQUAL "Android")
         SET(ANDROID TRUE)
+        INCLUDE(cross_compiling/android)
+    ELSEIF(${CMAKE_SYSTEM_NAME} STREQUAL "RPi")
+        SET(RPI TRUE)
+        INCLUDE(cross_compiling/raspberry_pi)
     ENDIF()
 ENDIF()
 
+# prefix and suffix on different os
+IF(WIN32)
+    SET(LIBRARY_PREFIX "")
+    SET(SHARED_LIBRARY_SUFFIX ".dll")
+    SET(STATIC_LIBRARY_SUFFIX ".lib")
+    SET(EXECUTABLE_SUFFIX ".exe")
+ELSE(WIN32)
+    SET(LIBRARY_PREFIX "lib")
+    IF(APPLE)
+        SET(SHARED_LIBRARY_SUFFIX ".dylib")
+    ELSE(APPLE)
+        SET(SHARED_LIBRARY_SUFFIX ".so")
+    ENDIF(APPLE)
+
+    SET(STATIC_LIBRARY_SUFFIX ".a")
+    SET(EXECUTABLE_SUFFIX "")
+ENDIF(WIN32)
+
 # external dependencies log output
 SET(EXTERNAL_PROJECT_LOG_ARGS
     LOG_DOWNLOAD    0     # Wrap download in script to log output