text: 
  
  if((NOT EIGEN3_INCLUDE_DIR) AND Eigen_SOURCE_DIR)
    # unless EIGEN3_INCLUDE_DIR is defined, let's use current Eigen version
    set(EIGEN3_INCLUDE_DIR ${Eigen_SOURCE_DIR})
    set(EIGEN3_FOUND TRUE)
  else()
    find_package(Eigen3)
  endif()
  
  if (EIGEN3_FOUND)
  
    include_directories(${EIGEN3_INCLUDE_DIR})
    btl_add_bench(btl_eigen3_linear main_linear.cpp)
    btl_add_bench(btl_eigen3_vecmat main_vecmat.cpp)
    btl_add_bench(btl_eigen3_matmat main_matmat.cpp)
    btl_add_bench(btl_eigen3_adv main_adv.cpp      )
  
    btl_add_target_property(btl_eigen3_linear COMPILE_FLAGS "-fno-exceptions -DBTL_PREFIX=eigen3")
    btl_add_target_property(btl_eigen3_vecmat COMPILE_FLAGS "-fno-exceptions -DBTL_PREFIX=eigen3")
    btl_add_target_property(btl_eigen3_matmat COMPILE_FLAGS "-fno-exceptions -DBTL_PREFIX=eigen3")
    btl_add_target_property(btl_eigen3_adv    COMPILE_FLAGS "-fno-exceptions -DBTL_PREFIX=eigen3")
  
    option(BTL_BENCH_NOGCCVEC "also bench Eigen explicit vec without GCC's auto vec" OFF)
    if(CMAKE_COMPILER_IS_GNUCXX AND BTL_BENCH_NOGCCVEC)
      btl_add_bench(btl_eigen3_nogccvec_linear main_linear.cpp)
      btl_add_bench(btl_eigen3_nogccvec_vecmat main_vecmat.cpp)
      btl_add_bench(btl_eigen3_nogccvec_matmat main_matmat.cpp)
      btl_add_bench(btl_eigen3_nogccvec_adv    main_adv.cpp   )
  
      btl_add_target_property(btl_eigen3_nogccvec_linear COMPILE_FLAGS "-fno-exceptions -fno-tree-vectorize -DBTL_PREFIX=eigen3_nogccvec")
      btl_add_target_property(btl_eigen3_nogccvec_vecmat COMPILE_FLAGS "-fno-exceptions -fno-tree-vectorize -DBTL_PREFIX=eigen3_nogccvec")
      btl_add_target_property(btl_eigen3_nogccvec_matmat COMPILE_FLAGS "-fno-exceptions -fno-tree-vectorize -DBTL_PREFIX=eigen3_nogccvec")
      btl_add_target_property(btl_eigen3_nogccvec_adv    COMPILE_FLAGS "-fno-exceptions -fno-tree-vectorize -DBTL_PREFIX=eigen3_nogccvec")
    endif()
  
  
    if(NOT BTL_NOVEC)
      btl_add_bench(btl_eigen3_novec_linear main_linear.cpp OFF)
      btl_add_bench(btl_eigen3_novec_vecmat main_vecmat.cpp OFF)
      btl_add_bench(btl_eigen3_novec_matmat main_matmat.cpp OFF)
      btl_add_bench(btl_eigen3_novec_adv main_adv.cpp       OFF)
      btl_add_target_property(btl_eigen3_novec_linear COMPILE_FLAGS "-fno-exceptions -DEIGEN_DONT_VECTORIZE -DBTL_PREFIX=eigen3_novec")
      btl_add_target_property(btl_eigen3_novec_vecmat COMPILE_FLAGS "-fno-exceptions -DEIGEN_DONT_VECTORIZE -DBTL_PREFIX=eigen3_novec")
      btl_add_target_property(btl_eigen3_novec_matmat COMPILE_FLAGS "-fno-exceptions -DEIGEN_DONT_VECTORIZE -DBTL_PREFIX=eigen3_novec")
      btl_add_target_property(btl_eigen3_novec_adv    COMPILE_FLAGS "-fno-exceptions -DEIGEN_DONT_VECTORIZE -DBTL_PREFIX=eigen3_novec")
  
  #     if(BUILD_btl_eigen3_adv)
  #       target_link_libraries(btl_eigen3_adv ${MKL_LIBRARIES})
  #     endif(BUILD_btl_eigen3_adv)
  
    endif(NOT BTL_NOVEC)
  
    btl_add_bench(btl_tiny_eigen3 btl_tiny_eigen3.cpp OFF)
  
    if(NOT BTL_NOVEC)
      btl_add_bench(btl_tiny_eigen3_novec btl_tiny_eigen3.cpp OFF)
      btl_add_target_property(btl_tiny_eigen3_novec    COMPILE_FLAGS "-DBTL_PREFIX=eigen3_tiny")
  
      if(BUILD_btl_tiny_eigen3_novec)
        btl_add_target_property(btl_tiny_eigen3_novec    COMPILE_FLAGS "-DEIGEN_DONT_VECTORIZE -DBTL_PREFIX=eigen3_tiny_novec")
      endif(BUILD_btl_tiny_eigen3_novec)
    endif(NOT BTL_NOVEC)
  
  endif (EIGEN3_FOUND)
  