From the GHDL GitHub site, we learn that one can use a prebuilt version of GHDL.
A directory for the download can be created, as
mkdir -p $HOME/sw_download/ghdl
cd $HOME/sw_download/ghdl
From this page with GHDL releases, a prebuilt version can be downloaded, as
curl -L https://github.com/ghdl/ghdl/releases/download/nightly/ghdl-macos-10.15-mcode.tgz --output ghdl-macos-10.15-mcode.tgz
After unpacking, as
tar zxvf ghdl-macos-10.15-mcode.tgz
and moving the unpacked content to a directory created and chosen for the GHDL installation, as
mkdir -p $HOME/sw/ghdl
mv bin $HOME/sw/ghdl
mv include $HOME/sw/ghdl
mv lib $HOME/sw/ghdl
we can try the installation on an example.
Assuming that ghdl is in the PATH environment variable, either by sourcing the file mac.sh or by a command, such as
export PATH=$HOME/sw/ghdl/bin:$PATH
we can try the installed GHDL on an example, with VHDL code in a file hello.vhdl as
ghdl -a hello.vhdl
ghdl -r hello_world
with a resulting printout, as
Hello, world