Compile for armv8.

cmake/cross_compiling/android.cmake

@@ -106,6 +106,9 @@ IF("${CMAKE_VERSION}" VERSION_LESS "3.7.0")
                 SET(CMAKE_SYSTEM_PROCESSOR armv7-a)
             ENDIF()
         ENDIF()
+        IF(ANDROID_ABI STREQUAL "arm64-v8a")
+            SET(ANDROID_TOOLCHAIN_NAME aarch64-linux-android)
+        ENDIF()
         SET(ANDROID_TOOLCHAIN_PREFIX "${ANDROID_TOOLCHAIN_ROOT}/bin/${ANDROID_TOOLCHAIN_NAME}-")
     ENDIF()
 
@@ -162,6 +165,10 @@ IF("${CMAKE_VERSION}" VERSION_LESS "3.7.0")
         ENDIF()
     ENDIF()
 
+    IF(ANDROID_ABI STREQUAL "arm64-v8a")
+      LIST(APPEND ANDROID_COMPILER_FLAGS -march=armv8-a)
+    ENDIF()
+
     STRING(REPLACE ";" " " ANDROID_COMPILER_FLAGS "${ANDROID_COMPILER_FLAGS}")
     STRING(REPLACE ";" " " ANDROID_LINKER_FLAGS "${ANDROID_LINKER_FLAGS}")
 

cmake/external/openblas.cmake

@@ -32,7 +32,12 @@ IF(NOT ${CBLAS_FOUND})
             # arm_soft_fp_abi branch of OpenBLAS to support softfp
             #   https://github.com/xianyi/OpenBLAS/tree/arm_soft_fp_abi
             SET(OPENBLAS_COMMIT "b5c96fcfcdc82945502a2303116a64d89985daf5")
-            SET(OPTIONAL_ARGS HOSTCC=${HOST_C_COMPILER} TARGET=ARMV7 ARM_SOFTFP_ABI=1 USE_THREAD=0)
+            IF(ANDROID_ABI MATCHES "^armeabi(-v7a)?$")
+                SET(TARGET "ARMV7")
+            ELSEIF(ANDROID_ABI STREQUAL "arm64-v8a")
+                SET(TARGET "ARMV8")
+            ENDIF()
+            SET(OPTIONAL_ARGS HOSTCC=${HOST_C_COMPILER} TARGET=${TARGET} ARM_SOFTFP_ABI=1 USE_THREAD=0)
         ELSEIF(RPI)
             # use hardfp
             SET(OPENBLAS_COMMIT "v0.2.19")