implement an even lower level version of the gebp kernel for MSVC (it seems to be faster with gcc as well) (transplanted from 9a5643551fe068497f84a81cd8986febf1918382)
implement an even lower level version of the gebp kernel for MSVC (it seems to be faster with gcc as well)
(transplanted from 9a5643551fe068497f84a81cd8986febf1918382)

--HG--
extra : transplant_source : %9AVCU%1F%E0hI%7F%84%A8%1C%D8%98o%EB%F1%91%83%82

madlib/eigen_backup,madlib/eigen_backup,rotorliu/eigen,rotorliu/eigen,rotorliu/eigen,mjbshaw/Eigen,mjbshaw/Eigen,mjbshaw/Eigen,rotorliu/eigen,madlib/eigen_backup,madlib/eigen_backup,mjbshaw/Eigen