This is the README from the source distribution of GHDL.

To get the binary distribution or more information, go to:
 https://github.com/tgingold/ghdl

Copyright:
**********
GHDL is copyright (c) 2002 - 2015 Tristan Gingold.
See the GHDL manual for more details.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.


Building GHDL from sources:
***************************

See BUILD.txt

There is a mailing list for any questions.  You can subscribe via:
  https://mail.gna.org/listinfo/ghdl-discuss/
Please report bugs on https://github.com/tgingold/ghdl/issues

If you cannot compile, please report the gcc version, GNAT version and gcc
source version.

* Note for ppc64 (and AIX ?) platform:
The object file format contains an identifier for the source language. Because
gcc doesn't know about the VHDL, gcc crashes very early. This could be fixed
with a very simple change in gcc/config/rs6000/rs6000.c,
function rs6000_output_function_epilogue (as of gcc 4.8):
       else if (! strcmp (language_string, "GNU Objective-C"))
        i = 14;
       else
-       gcc_unreachable ();
+       i = 0;
       fprintf (file, "%d,", i);

       /* 8 single bit fields: global linkage (not set for C extern linkage,

Tristan Gingold.