add openmp support

CMakeLists.txt

 cmake_minimum_required(VERSION 3.6)
+option(USE_OPENMP "openmp support" ON)
+
 project(paddle-mobile)
 
 option(DEBUGING "enable debug mode" OFF)
-option(USE_OPENMP "openmp support" OFF)
 option(USE_EXCEPTION "use std exception" OFF)
 option(LOG_PROFILE "log profile" OFF)
 # select the platform to build

src/ios_io/PaddleMobile.mm

@@ -58,6 +58,7 @@ static std::mutex shared_mutex;
 - (BOOL)load:(NSString *)modelPath andWeightsPath:(NSString *)weighsPath{
   std::string model_path_str = std::string([modelPath UTF8String]);
   std::string weights_path_str = std::string([weighsPath UTF8String]);
+  pam_->SetThreadNum(2);
   if (loaded_ = pam_->Load(model_path_str, weights_path_str, true)) {
     return YES;
   } else {

tools/ios-cmake/ios.toolchain.cmake

@@ -50,8 +50,13 @@ endif (CMAKE_UNAME)
 #include (CMakeForceCompiler)
 #CMAKE_C_COMPILER (/usr/bin/gcc)
 #CMAKE_CXX_COMPILER (/usr/bin/g++)
-set(CMAKE_C_COMPILER /usr/bin/gcc)
-set(CMAKE_CXX_COMPILER /usr/bin/g++)
+if(USE_OPENMP)
+    set(CMAKE_C_COMPILER /usr/local/opt/llvm/bin/clang)
+    set(CMAKE_CXX_COMPILER /usr/local/opt/llvm/bin/clang++)
+else()
+    set(CMAKE_C_COMPILER /usr/bin/gcc)
+    set(CMAKE_CXX_COMPILER /usr/bin/g++)
+endif()
 set(CMAKE_AR ar CACHE FILEPATH "" FORCE)
 
 # Skip the platform compiler checks for cross compiling