enable arm math lib

paddle/fluid/lite/arm/math/CMakeLists.txt

@@ -6,8 +6,47 @@ if(NOT (LITE_WITH_LIGHT_WEIGHT_FRAMEWORK AND LITE_WITH_ARM))
   return()
 endif()
 
-# TODO(xxx): seperate them
-lite_cc_library(math_arm SRCS
+set(HAS_ARM_MATH_LIB_DIR OFF)
+# will search name as "libmath_arm.${os}.${abi}.${lang}.a"
+if(ARM_MATH_LIB_DIR AND EXISTS "${ARM_MATH_LIB_DIR}")
+  set(arm_math_name "")
+  if(ARM_TARGET_OS STREQUAL "android")
+    if(ARM_TARGET_ARCH_ABI STREQUAL "armv8")
+      set(arm_math_name "math_arm.android.armv8")
+    elseif(ARM_TARGET_ARCH_ABI STREQUAL "armv7")
+      set(arm_math_name "math_arm.android.armv7")
+    endif()
+  endif()
+
+  if(ARM_TARGET_OS STREQUAL "armlinux" )
+    if(ARM_TARGET_ARCH_ABI STREQUAL "armv8")
+      set(arm_math_name "math_arm.armlinux.armv8")
+    elseif(ARM_TARGET_ARCH_ABI STREQUAL "armv7")
+      set(arm_math_name "math_arm.armlinux.armv7")
+    endif()
+  endif()
+
+  if(ARM_TARGET_LANG STREQUAL "clang")
+    set(arm_math_name "${arm_math_name}.clang")
+  else()
+    set(arm_math_name "${arm_math_name}.gcc")
+  endif()
+
+  find_library(math_arm_file ${arm_math_name} ${ARM_MATH_LIB_DIR} NO_DEFAULT_PATH)
+  if(math_arm_file)
+    add_library(math_arm STATIC IMPORTED GLOBAL)
+    set_property(TARGET math_arm PROPERTY IMPORTED_LOCATION ${math_arm_file})
+    message(STATUS "ARM math library imported: ${math_arm_file}")
+    set(HAS_ARM_MATH_LIB_DIR ON)
+  else()
+    message(WARNING "Can not find arm math library ${arm_math_name} in ${ARM_MATH_LIB_DIR")
+  endif()
+endif()
+
+
+if (NOT HAS_ARM_MATH_LIB_DIR)
+  # TODO(xxx): seperate them and do not deps proto, eigen3
+  cc_library(math_arm SRCS  
       funcs.cc 
       packed_sgemm.cc 
       softmax.cc 
@@ -40,6 +79,4 @@ lite_cc_library(math_arm SRCS
       conv3x3s1_direct_int8.cc
       conv3x3s2_direct_int8.cc
       DEPS ${lite_kernel_deps} eigen3 framework_proto_lite)
-  # TODO(TJ): fix me do not deps proto
- 
- 
+endif()