Building GCC 1.27 (2019)

# Building GCC 1.27 Source: [http://kristerw.blogspot.com/2019/01/building-gcc-127.html](http://kristerw.blogspot.com/2019/01/building-gcc-127.html) GCC 1\.27 was released in 1988 and is the first version of GCC supporting the x86 CPU\. I thought it would be fun to make it work on my desktop computer\. Mikhail Maltsev wrote a great blog post about this a while back “[Building and using a 29\-year\-old compiler on a modern system](https://miyuki.github.io/2017/10/04/gcc-archaeology-1.html)”\. I used Mikhail’s work as a starting point, but I built on a 64\-bit Ubuntu system so I needed to update paths and`as`/`ld`options for running on a 64\-bit OS, and I had much bigger problems with the ancient GCC not understanding the system headers\. I also enabled the DBX debug format instead of the UNIX/32V SDB format that GDB does not understand\. But I did not need to make that big changes to Mikhail’s patch\. It is amazing how well things work – the modern assembler, linker, and debugger handles the code generated by GCC 1\.27 without any problems\. And command options such as`\-O`,`\-E`,`\-S`,`\-c`,`\-g`,`\-W`,`\-pedantic`, and`\-fomit\-frame\-pointer`does what you expect from using a modern GCC\. All the options are documented in the manual page – you can format the text by passing the`gcc\.1`file to`man`as ``` man -l gcc.1 ``` ### How to build GCC 1\.27 on Ubuntu I have built the compiler on 64\-bit Ubuntu Desktop 16\.04 as described below\. #### Prerequisites GCC 1\.27 is a 32\-bit program, so we need to install 32\-bit compiler and runtime support ``` sudo apt install gcc-multilib ``` #### Downloading and preparing the source code Download the source code and the patch, and apply the patch as ``` wget https://gcc.gnu.org/pub/gcc/old-releases/gcc-1/gcc-1.27.tar.bz2 wget https://gist.github.com/kristerw/b854b6d285e678452a44a6bcbf7ef86f/raw/gcc-1.27.patch tar xf gcc-1.27.tar.bz2 cd gcc-1.27 patch -p1 < ../gcc-1.27.patch ``` #### Configuring the source code The compiler is configured by setting up symbolic links to the correct configuration files ``` ln -s config-i386v.h config.h ln -s tm-i386v.h tm.h ln -s i386.md md ln -s output-i386.c aux-output.c ``` You may want to change where the compiler is installed by updating`bindir`and`libdir`in the`Makefile`\. I set them to ``` bindir = /home/kristerw/compilers/gcc-1.27/bin libdir = /home/kristerw/compilers/gcc-1.27/lib ``` #### Build and install The compiler is built in two \(or three\) stages, We start by building it using the system compiler ``` make ``` We then build it again using the newly built compiler ``` make stage1 make CC=stage1/gcc CFLAGS="-O -Bstage1/ -Iinclude" ``` As a third, optional, step, we build it again using the second compiler and checks that the resulting binaries are identical with the second compiler \(if not, then the compiler has miscompiled itself\)\. ``` make stage2 make CC=stage2/gcc CFLAGS="-O -Bstage2/ -Iinclude" diff cpp stage2/cpp diff gcc stage2/gcc diff cc1 stage2/cc1 ``` We are now ready to install the compiler ``` make install ```