[Core] Support Clang toolchains for Android (#3107)

* [CORE] Support Clang compiling for Android
test=develop

* fix lto for jni so
test=develop

* disable assembly code
test=develop

* disable layout.cc
test=develop

* refine
test=develop

* Enable LTO on Clang
test=develop

* Disable LTO when clang is used.
test=develop

* Remove space
test=develop

* [Core] enable clang in build.sh
test=develop

* [Core] Remove the workaround for clang compiling
test=develop

cmake/cross_compiling/postproject.cmake

@@ -60,16 +60,11 @@ endfunction()
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
 if (LITE_ON_TINY_PUBLISH)
     if(NOT LITE_WITH_PYTHON)
-	    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-exceptions")
-    endif()
-    if(ARM_TARGET_LANG STREQUAL "clang")
-        # TODO(ysh329): add options for clang like gcc branch below
-    else() # ARM_TARGET_LANG STREQUAL "gcc"
-        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ffast-math -Ofast -Os -fomit-frame-pointer -fno-asynchronous-unwind-tables -fno-unwind-tables")
-        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fvisibility=hidden -fvisibility-inlines-hidden -ffunction-sections")
-        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fvisibility-inlines-hidden -ffunction-sections")
-        check_linker_flag(-Wl,--gc-sections)
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-exceptions")
     endif()
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ffast-math -Ofast -Os -fomit-frame-pointer -fno-asynchronous-unwind-tables -fno-unwind-tables")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fvisibility=hidden -fvisibility-inlines-hidden -ffunction-sections")
+    check_linker_flag(-Wl,--gc-sections)
 endif()
 
 if(LITE_WITH_OPENMP)

lite/api/CMakeLists.txt

@@ -5,13 +5,8 @@ else()
 endif(LITE_WITH_LIGHT_WEIGHT_FRAMEWORK)
 
 if (LITE_ON_TINY_PUBLISH)
-    if(ARM_TARGET_LANG STREQUAL "clang")
-        set(CMAKE_CXX_FLAGS_RELEASE " -DNDEBUG")
-        set(CMAKE_C_FLAGS_RELEASE " -DNDEBUG")
-    else() # gcc
-        set(CMAKE_CXX_FLAGS_RELEASE "-Os -DNDEBUG")
-        set(CMAKE_C_FLAGS_RELEASE "-Os -DNDEBUG")
-    endif()
+    set(CMAKE_CXX_FLAGS_RELEASE "-Os -DNDEBUG")
+    set(CMAKE_C_FLAGS_RELEASE "-Os -DNDEBUG")
 endif()
 set(light_lib_DEPS light_api paddle_api paddle_api_light optimizer)
 if ((NOT LITE_ON_TINY_PUBLISH) AND (LITE_WITH_CUDA OR LITE_WITH_X86 OR ARM_TARGET_OS STREQUAL "android" OR ARM_TARGET_OS STREQUAL "armlinux"))
@@ -50,11 +45,11 @@ else()
     if ((ARM_TARGET_OS STREQUAL "android") OR (ARM_TARGET_OS STREQUAL "armlinux"))
         add_library(paddle_light_api_shared SHARED "")
         target_sources(paddle_light_api_shared PUBLIC ${__lite_cc_files} paddle_api.cc light_api.cc light_api_impl.cc)
-        if(ARM_TARGET_LANG STREQUAL "clang")
-            set_target_properties(paddle_light_api_shared PROPERTIES COMPILE_FLAGS "")
-        else() # ARM_TARGET_LANG STREQUAL "gcc"
-            set_target_properties(paddle_light_api_shared PROPERTIES COMPILE_FLAGS "-flto -fdata-sections")
+        set(TARGET_COMIPILE_FLAGS "-fdata-sections")
+        if (NOT (ARM_TARGET_LANG STREQUAL "clang")) #gcc
+            set(TARGET_COMIPILE_FLAGS "${TARGET_COMIPILE_FLAGS} -flto")
         endif()
+        set_target_properties(paddle_light_api_shared PROPERTIES COMPILE_FLAGS "${TARGET_COMIPILE_FLAGS}")
         add_dependencies(paddle_light_api_shared op_list_h kernel_list_h)
         if (LITE_WITH_NPU)
             # Need to add HIAI runtime libs (libhiai.so) dependency

lite/api/android/jni/native/CMakeLists.txt

 # Generate paddle_lite_jni.so
 
 if (LITE_ON_TINY_PUBLISH)
-    if(ARM_TARGET_LANG STREQUAL "clang")
-        set(CMAKE_CXX_FLAGS_RELEASE "-DNDEBUG")
-        set(CMAKE_C_FLAGS_RELEASE "-DNDEBUG")
-    else() # ARM_TARGET_LANG STREQUAL "gcc"
-        set(CMAKE_CXX_FLAGS_RELEASE "-Os -DNDEBUG")
-        set(CMAKE_C_FLAGS_RELEASE "-Os -DNDEBUG")
-    endif()
+    set(CMAKE_CXX_FLAGS_RELEASE "-Os -DNDEBUG")
+    set(CMAKE_C_FLAGS_RELEASE "-Os -DNDEBUG")
     set(lib_DEPS light_api paddle_api paddle_api_light)
 else()
     set(lib_DEPS light_api cxx_api paddle_api_full paddle_api paddle_api_light)
@@ -30,11 +25,11 @@ if (NOT LITE_ON_TINY_PUBLISH)
     endif()
 else()
     add_library(paddle_lite_jni SHARED "")
-    if(ARM_TARGET_LANG STREQUAL "clang")
-        set_target_properties(paddle_lite_jni PROPERTIES COMPILE_FLAGS "")
-    else() # ARM_TARGET_LANG STREQUAL "gcc"
-        set_target_properties(paddle_lite_jni PROPERTIES COMPILE_FLAGS "-flto -fdata-sections")
+    set(TARGET_COMIPILE_FLAGS "-fdata-sections")
+    if (NOT (ARM_TARGET_LANG STREQUAL "clang")) #gcc
+        set(TARGET_COMIPILE_FLAGS "${TARGET_COMIPILE_FLAGS} -flto")
     endif()
+    set_target_properties(paddle_lite_jni PROPERTIES COMPILE_FLAGS ${TARGET_COMIPILE_FLAGS})
     target_sources(paddle_lite_jni PUBLIC ${__lite_cc_files} paddle_lite_jni.cc tensor_jni.cc)
     add_dependencies(paddle_lite_jni op_list_h kernel_list_h)
     if (LITE_WITH_NPU)

lite/tools/build.sh

@@ -390,13 +390,6 @@ function main {
                 ;;
             --arm_lang=*)
                 ARM_LANG="${i#*=}"
-                if [ ${ARM_LANG} == "clang" ]; then
-                     set +x
-                     echo
-                     echo -e "error: only support gcc now, clang will be supported in future."
-                     echo
-#                     exit 1
-                fi
                 shift
                 ;;
             --android_stl=*)