gcc-5.3 installation on Ubuntu 18 (to enable cuda 9.1 + NVIDIA 390)

gcc_5.3_installation_guideline.txt

# ================= Removing all gcc/g++ and clean build
sudo apt-get remove gcc-7
sudo apt-get remove g++-7
sudo apt-get purge gcc-7* g++-7*
sudo apt autoremove


  # =======================================
  Make sure the default displays are running fine. If not: install the following
  sudo apt-get install ubuntu-desktop xorg xserver-xorg-core xserver-xorg gdm3 libubsan0* ubuntu-desktop
  x11-session-utils x11-xserver-utils xorg

# ======================
# Add gcc-6 (If you do an ap-get install, it will not really work)
sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt update
sudo apt install --reinstall gcc-6
sudo apt install --reinstall g++-6

sudo update-alternatives --force --all

When you get the options for gcc: choose gcc-6 (below example 1)

  0            /usr/bin/gcc-7   100       auto mode
* 1            /usr/bin/gcc-6   60        manual mode
  2            /usr/bin/gcc-7   100       manual mode
  
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-6 60 --slave /usr/bin/g++ g++ /usr/bin/g++-6

Note: Some people have reported that their NVIDIA+CUDA9.1 installation on Ubuntu 18 works perfectly with gcc-6. I wasn't that lucky, so I continue installing gcc-5.3
Give the NVIDIA+CUDA Installation a try. If it fails, then purge nvidia+cuda+clean and repeat all of the above and proceed with gcc-5.3 installation
Because the creepy Debian packages tries to sneak in the gcc-7 default compiler with any random package installation. And it gets messing up the cuda installation

# ==================== Now install 5.3
Download the gcc tar folder from here https://ftp.gnu.org/gnu/gcc/gcc-5.3.0/ & extract 
mkdir build
cd build

You will get errors related to std98
Make the changes to the files as described in the patch here
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=ec1cc0263f156f70693a62cf17b254a0029f4852

 # --------------------------
Change 2: libgcc/config/i386/linux_unwind.h
Next, In linux_unwind.h , on line 61, you have to change 
  struct ucontext *uc_ = context->cfa; ==> to struct ucontext_t *uc_ = context->cfa
 
 # --------------------------
Change 3: ../libsanitizer/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc 
error: aggregate ‘sigaltstack handler_stack’ has incomplete type and cannot be defined
   struct sigaltstack handler_stack;
   
  Make the changes below:
  
          // Alternate stack for signal handling.
         InternalScopedBuffer<char> handler_stack_memory(kHandlerStackSize);
      -  struct sigaltstack handler_stack;
      +  stack_t handler_stack;
         internal_memset(&handler_stack, 0, sizeof(handler_stack));
         handler_stack.ss_sp = handler_stack_memory.data();
         handler_stack.ss_size = kHandlerStackSize;
      --- libsanitizer/sanitizer_common/sanitizer_linux.cc	2015-11-23 10:07:18.000000000 +0100
      +++ libsanitizer/sanitizer_common/sanitizer_linux.cc	2017-08-05 19:03:06.916498311 +0200
      @@ -546,8 +546,7 @@
       }
       #endif

      -uptr internal_sigaltstack(const struct sigaltstack *ss,
      -                         struct sigaltstack *oss) {
      +uptr internal_sigaltstack(const void *ss, void *oss) {
         return internal_syscall(SYSCALL(sigaltstack), (uptr)ss, (uptr)oss);
       }
 
 # --------- Change 4 ------------
libsanitizer/sanitizer_common/sanitizer_linux.h, Around line 20, make this change

struct link_map;  // Opaque type returned by dlopen().
 namespace __sanitizer {

  
  Make this change as well (line 28)
 // Syscall wrappers.
 uptr internal_getdents(fd_t fd, struct linux_dirent *dirp, unsigned int count);
-uptr internal_sigaltstack(const struct sigaltstack* ss,
-                          struct sigaltstack* oss);
+uptr internal_sigaltstack(const void* ss, void* oss);
 uptr internal_sigprocmask(int how, __sanitizer_sigset_t *set,
     __sanitizer_sigset_t *oldset);
 void internal_sigfillset(__sanitizer_sigset_t *set);

# -----------
libsanitizer/tsan/tsan_platform_linux.cc
#if SANITIZER_LINUX 
   int cnt = 0;
-  __res_state *statp = (__res_state*)state;
+  struct __res_state *statp = (struct __res_state*)state;
   for (int i = 0; i < MAXNS && cnt < nfd; i++) {
     if (statp->_u._ext.nsaddrs[i] && statp->_u._ext.nssocks[i] != -1)
       fds[cnt++] = statp->_u._ext.nssocks[i];

 # ----------- Change 6 ----
In libsanitizer/asan/asan_linux.cc, Add the lin ebelow
#include <signal.h>

##--------------- That's All !----------------------------
The make process will take a really long long time, Go make coffee(rather grow coffee beans) in the meanwhile :-/

then run 
  sudo make install
  sudo ldconfig, blah blah blah...

sudo apt-get update
gcc --version ==> 5.3

sudo reboot now

After rebooting, 
press Ctrl + Alt + F7 to disable the display

vim /etc/modprobe.d/blacklist-nvidia-nouveau.conf
blacklist nouveau
options nouveau modeset=0

sudo update-initramfs -u
## =============================================
NVIDIA Driver Installation
  
ubuntu-drivers devices
apt-get purge nvidia* && apt-get autoremove

Download NVIDIA 390 drivers (.sh) file and install
If you are getting the nouveau problems, and unable to install there's an alternate way :-/
Sudo apt-get install nvidia-driver-390
This is gonna freak set gcc7 or gcc6 as default compiler. No Worries
cd gcc-5.3 && sudo make install && sudo ldconfig && gcc --version ==> magic

# Cuda 9/8/7 Reuirements 
sudo apt-get install freeglut3-dev build-essential libx11-dev libxmu-dev libxi-dev libgl1-mesa-glx libglu1-mesa libglu1-mesa-dev libglfw3-dev libgles2-mesa-dev

# Installing Cuda 8 on Ubuntu 18
If outputs error 'Can't locate InstallUtils.pm in @INC'
Then do this,
  Can't locate InstallUtils.pm in @INC
  sudo cp ./InstallUtils.pm /usr/lib/x86_64-linux-gnu/perl-base/
  export $PERL5LIB

Download the CUDA 9.1 run file (only upto Ubuntu 17 is available)
Say no when it asks if NVIDIA 387 driver needs to be installed

Download CUDNN 5, 6, 7
Sudo ln the required library and install them as usual

Download NCCL for Cuda 8/9
https://docs.nvidia.com/deeplearning/sdk/nccl-install-guide/index.html
Add the PPA && apt update && sudo apt-get install libnccl2=2.2.13-1+cuda8.0 libnccl-dev=2.2.13-1+cuda8.0