fully adapt the gebp kernel and optimize it for CPU with only 8 registers
fully adapt the gebp kernel and optimize it for CPU with only 8 registers

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