wget https://gmplib.org/download/gmp/gmp-6.1.2.tar.xz
tar xvf gmp-6.1.2.tar.xz 
cd gmp-6.1.2
./configure --prefix=/usr/local/gmp
make && make install

wget http://www.mpfr.org/mpfr-current/mpfr-3.1.6.tar.gz
tar xvf mpfr-3.1.6.tar.gz 
cd mpfr-3.1.6
./configure --prefix=/usr/local/mpfr --with-gmp=/usr/local/gmp
make && make install

wget ftp://ftp.gnu.org/gnu/mpc/mpc-1.0.3.tar.gz
tar xvf mpc-1.0.3.tar.gz 
cd mpc-1.0.3
./configure --prefix=/usr/local/mpc --with-gmp=/usr/local/gmp -with-mpfr=/usr/local/mpfr
make && make install

vi /etc/ld.so.conf
#增加以下三行
/usr/local/gmp/lib
/usr/local/mpfr/lib
/usr/local/mpc/lib
#
ldconfig -v

wget ftp://ftp.gnu.org/gnu/gcc/gcc-6.4.0/gcc-6.4.0.tar.gz
tar xvf gcc-6.4.0.tar.gz
./configure --enable-checking=release --enable-languages=c,c++ --disable-multilib --with-gmp=/usr/local/gmp --with-mpfr=/usr/local/mpfr --with-mpc=/usr/local/mpc
make -j2 # 这个过程比较慢, 大概要半个多小时
make install
# 改名 /usr/bin 下的 cpp, c++, gcc, g++, gcov 这些文件, 再执行 gcc --version 就能看到新的版本信息了