安装到本地指定目录，先指定本地目录为home目录下的local。并导入到path中
export LOCAL_LIBS=$HOME/local/
mkdir $LOCAL_LIBS
export PATH=$LOCAL_LIBS/bin:$LOCAL_LIBS/usr/local/bin/:$PATH

开始下载gcc后解压
下载地址：https://gcc.gnu.org/
tar -zxvf gcc-8.2.0.tar.gz
./configure --prefix=$LOCAL_LIBS
编译后报错

configure: error: Building GCC requires GMP 4.2+, MPFR 2.4.0+ and MPC 0.8.0+.

需要依赖 mpc，mpfr，gmp包，
GCC 源码里自带脚本可以轻松下载依赖包。
./contrib/download_prerequisites
如果能联网的话最后成功后是这样的：
$ ./contrib/download_prerequisites
gmp-6.1.0.tar.bz2: OK
mpfr-3.1.4.tar.bz2: OK
mpc-1.0.3.tar.gz: OK
isl-0.18.tar.bz2: OK
All prerequisites downloaded successfully.

如果不能联网，则需要自己手动下载到本地
ftp://gcc.gnu.org/pub/gcc/infrastructure/在这个网址中找到需要依赖的三个包，下载到本地先安装这三个包
安装第一个；是有顺序的。

tar jxvf gmp-6.1.0.tar.bz2
./configure --prefix=$LOCAL_LIBS
make
make install

安装成功，这里先把安装成功后的部分信息粘贴在这里，

Libraries have been installed in:
   /BIGDATA1/cygene_sydu_1/local/lib

If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the '-LLIBDIR'
flag during linking and do at least one of the following:
   - add LIBDIR to the 'LD_LIBRARY_PATH' environment variable
     during execution
   - add LIBDIR to the 'LD_RUN_PATH' environment variable
     during linking
   - use the '-Wl,-rpath -Wl,LIBDIR' linker flag
   - have your system administrator add LIBDIR to '/etc/ld.so.conf'

See any operating system documentation about shared libraries for
more information, such as the ld(1) and ld.so(8) manual pages.
----------------------------------------------------------------------
 /bin/mkdir -p '/BIGDATA1/cygene_sydu_1/local/include'
 /usr/bin/install -c -m 644 gmp.h '/BIGDATA1/cygene_sydu_1/local/include'
make  install-data-hook
make[4]: Entering directory `/BIGDATA1/cygene_sydu_1/software/gmp-6.1.0'

+-------------------------------------------------------------+
| CAUTION:                                                    |
|                                                             |
| If you have not already run "make check", then we strongly  |
| recommend you do so.                                        |
|                                                             |
| GMP has been carefully tested by its authors, but compilers |
| are all too often released with serious bugs.  GMP tends to |
| explore interesting corners in compilers and has hit bugs   |
| on quite a few occasions.                                   |
|                                                             |
+-------------------------------------------------------------+

make[4]: Leaving directory `/BIGDATA1/cygene_sydu_1/software/gmp-6.1.0'
make[3]: Leaving directory `/BIGDATA1/cygene_sydu_1/software/gmp-6.1.0'
make[2]: Leaving directory `/BIGDATA1/cygene_sydu_1/software/gmp-6.1.0'
make[1]: Leaving directory `/BIGDATA1/cygene_sydu_1/software/gmp-6.1.0'

第二个

tar  jxvf mpfr-3.1.4.tar.bz2
cd mpfr-3.1.4
./configure --prefix=$LOCAL_LIBS
make 
make install

安装成功后会有：

Libraries have been installed in:
   /BIGDATA1/cygene_sydu_1/local/lib

If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the '-LLIBDIR'
flag during linking and do at least one of the following:
   - add LIBDIR to the 'LD_LIBRARY_PATH' environment variable
     during execution
   - add LIBDIR to the 'LD_RUN_PATH' environment variable
     during linking
   - use the '-Wl,-rpath -Wl,LIBDIR' linker flag
   - have your system administrator add LIBDIR to '/etc/ld.so.conf'

安装第三个：

tar zxvf mpc-1.0.3.tar.gz
cd mpc-1.0.3
./configure --prefix=$LOCAL_LIBS  LDFLAGS="-L/BIGDATA1/cygene_sydu_1/local/lib" CPPFLAGS="-I/BIGDATA1/cygene_sydu_1/local/include"
make
make install

然后安装gcc

cd gcc-8.2.0
./configure --prefix=$LOCAL_LIBS  LDFLAGS="-L/BIGDATA1/cygene_sydu_1/local/lib" CPPFLAGS="-I/BIGDATA1/cygene_sydu_1/local/include"

安装报错：
required isl version is 0.15 or later
下载安装isl，还是在刚才下载mpc的网址中下载

tar jxvf isl-0.18.tar.bz2
cd isl-0.18
./configure --prefix=$LOCAL_LIBS  LDFLAGS="-L/BIGDATA1/cygene_sydu_1/local/lib" CPPFLAGS="-I/BIGDATA1/cygene_sydu_1/local/include"
make
make install

没有报错，isl安装完成，
继续编译gcc：

./configure --prefix=$LOCAL_LIBS  LDFLAGS="-L/BIGDATA1/cygene_sydu_1/local/lib" CPPFLAGS="-I/BIGDATA1/cygene_sydu_1/local/include"
···
checking for isl 0.15 or later... yes
The following languages will be built: c,c++,fortran,lto,objc
*** This configuration is not supported in the following subdirectories:
     gnattools gotools target-libada target-libhsail-rt target-libgo target-libffi target-liboffloadmic
    (Any other directories should still work fine.)
checking for default BUILD_CONFIG... bootstrap-debug
checking for --enable-vtable-verify... no
/usr/bin/ld: crt1.o: No such file: No such file or directory
collect2: ld returned 1 exit status
configure: error: I suspect your system does not have 32-bit development libraries (libc and headers). If you have them, rerun configure with --enable-multilib. If you do not have them, and want to build a 64-bit-only compiler, rerun configure with --disable-multilib.

编译报错，根据提示，加上--disable-multilib参数再编译一次

./configure --prefix=$LOCAL_LIBS  LDFLAGS="-L/BIGDATA1/cygene_sydu_1/local/lib" CPPFLAGS="-I/BIGDATA1/cygene_sydu_1/local/include" --disable-multilib
make

make报错了

In file included from ../.././gcc/c/c-decl.c:53:
../.././gcc/builtins.h:23:17: warning: mpc.h: No such file or directory
In file included from ../.././gcc/c/c-decl.c:53:
../.././gcc/builtins.h:87: error: expected ‘,’ or ‘...’ before ‘(’ token
make[3]: *** [c/c-decl.o] Error 1
make[3]: Leaving directory `/BIGDATA1/cygene_sydu_1/software/gcc-8.2.0/host-x86_64-pc-linux-gnu/gcc'
make[2]: *** [all-stage1-gcc] Error 2
make[2]: Leaving directory `/BIGDATA1/cygene_sydu_1/software/gcc-8.2.0'
make[1]: *** [stage1-bubble] Error 2
make[1]: Leaving directory `/BIGDATA1/cygene_sydu_1/software/gcc-8.2.0'
make: *** [all] Error 2

愁死人了

总结

当安装到指定目录时候，再没有root权限的情况下，可以通过指定LDFLAGS和CPPFLAGS，将安装的依赖包的lib和include路径指定。就可以编译成功了，