gcc/contrib/vim-gcc-dev/README

This directory serves as a simple Vim addon for GCC development.  It can be
symlinked or copied into Vim plugin directory as any other plugin.  For
example, if using vim-pathogen plugin manager:

    ln -s /path/to/gcc/contrib/vim-gcc-dev ~/.vim/bundle/

This adds syntax highlighting rules for the match.pd file and GIMPLE/RTL dumps.

You can also use RTL syntax rules for GCC machine desciption files by adding

    autocmd BufRead *.md  setf gcc-rtl

to your ~/.vimrc file.