NEON instruction set control unified for regular and cross-compiler builds.

CMakeLists.txt

@@ -214,6 +214,8 @@ OCV_OPTION(ENABLE_SSSE3               "Enable SSSE3 instructions"
 OCV_OPTION(ENABLE_SSE41               "Enable SSE4.1 instructions"                               OFF  IF ((CV_ICC OR CMAKE_COMPILER_IS_GNUCXX) AND (X86 OR X86_64)) )
 OCV_OPTION(ENABLE_SSE42               "Enable SSE4.2 instructions"                               OFF  IF (CMAKE_COMPILER_IS_GNUCXX AND (X86 OR X86_64)) )
 OCV_OPTION(ENABLE_AVX                 "Enable AVX instructions"                                  OFF  IF ((MSVC OR CMAKE_COMPILER_IS_GNUCXX) AND (X86 OR X86_64)) )
+OCV_OPTION(ENABLE_NEON                "Enable NEON instructions"                                 OFF  IF CMAKE_COMPILER_IS_GNUCXX AND ARM )
+OCV_OPTION(ENABLE_VFPV3               "Enable VFPv3-D32 instructions"                            OFF  IF CMAKE_COMPILER_IS_GNUCXX AND ARM )
 OCV_OPTION(ENABLE_NOISY_WARNINGS      "Show all warnings even if they are too noisy"             OFF )
 OCV_OPTION(OPENCV_WARNINGS_ARE_ERRORS "Treat warnings as errors"                                 OFF )
 OCV_OPTION(ENABLE_WINRT_MODE          "Build with Windows Runtime support"                       OFF  IF WIN32 )
@@ -240,6 +242,15 @@ include(cmake/OpenCVVersion.cmake)
 # Save libs and executables in the same place
 set(EXECUTABLE_OUTPUT_PATH "${CMAKE_BINARY_DIR}/bin" CACHE PATH "Output directory for applications" )
 
+if (ANDROID)
+  if (ANDROID_ABI MATCHES "NEON")
+    set(ENABLE_NEON ON)
+  endif()
+  if (ANDROID_ABI MATCHES "VFPV3")
+    set(ENABLE_VFPV3 ON)
+  endif()
+endif()
+
 if(ANDROID OR WIN32)
   set(OPENCV_DOC_INSTALL_PATH doc)
 elseif(INSTALL_TO_MANGLED_PATHS)

cmake/OpenCVCompilerOptions.cmake

@@ -130,6 +130,12 @@ if(CMAKE_COMPILER_IS_GNUCXX)
   if(ENABLE_SSE2)
     add_extra_compiler_option(-msse2)
   endif()
+  if (ENABLE_NEON)
+    add_extra_compiler_option("-mfpu=neon")
+  endif()
+  if (ENABLE_VFPV3 AND NOT ENABLE_NEON)
+    add_extra_compiler_option("-mfpu=vfpv3")
+  endif()
 
   # SSE3 and further should be disabled under MingW because it generates compiler errors
   if(NOT MINGW)

doc/tutorials/introduction/crosscompilation/arm_crosscompile_with_cmake.rst

@@ -106,8 +106,8 @@ Enable hardware optimizations
 -----------------------------
 
 Depending on target platform architecture different instruction sets can be used. By default
-compiler generates code for armv5l without VFPv3 and NEON extensions. Add ``-DUSE_VFPV3=ON``
-to cmake command line to enable code generation for VFPv3 and ``-DUSE_NEON=ON`` for using
+compiler generates code for armv5l without VFPv3 and NEON extensions. Add ``-DENABLE_VFPV3=ON``
+to cmake command line to enable code generation for VFPv3 and ``-DENABLE_NEON=ON`` for using
 NEON SIMD extensions.
 
 TBB is supported on multi core ARM SoCs also.

platforms/linux/arm-gnueabi.toolchain.cmake

@@ -28,14 +28,11 @@ set(CMAKE_MODULE_LINKER_FLAGS "-Wl,--fix-cortex-a8 -Wl,--no-undefined -Wl,--gc-s
 set(CMAKE_EXE_LINKER_FLAGS    "-Wl,--fix-cortex-a8 -Wl,--no-undefined -Wl,--gc-sections -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now ${CMAKE_EXE_LINKER_FLAGS}")
 
 if(USE_NEON)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpu=neon")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -mfpu=neon")
+  message(WARNING "You use obsolete variable USE_NEON to enable NEON instruction set. Use -DENABLE_NEON=ON instead." )
+  set(ENABLE_NEON TRUE)
 elseif(USE_VFPV3)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpu=vfpv3")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -mfpu=vfpv3")
-else()
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpu=vfpv3-d16")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -mfpu=vfpv3-d16")
+  message(WARNING "You use obsolete variable USE_VFPV3 to enable VFPV3 instruction set. Use -DENABLE_VFPV3=ON instead." )
+  set(ENABLE_VFPV3 TRUE)
 endif()
 
 set(CMAKE_FIND_ROOT_PATH ${CMAKE_FIND_ROOT_PATH} ${ARM_LINUX_SYSROOT})