Also, there are parts of the PathScale compiler suite that are not licensed under the GPLv3. The parts of their codebase that are not licensed under the GPLv3 don't have the same problem, even without a gcc exception. Let's enumerate the licenses one by one:
MIT/X11: A liberal license with no copyleft clause. You can make proprietary software with MIT/X11 licensed code.
BSD: same as above.
LGPL 2.1 or later: A copyleft license, but it explicitly allows you to make proprietary software with a derived work, as long as you don't modify the original works. So basically, as long as you don't modify the PathScale compiler or runtime while writing your C/C++ application, you can make it proprietary and comply with the LGPLed parts of the code.
The only code in question is GPLv3'ed code that is not part of the gcc frontend, but is written by the PathScale developers. If, indeed, such code exists, and is not licensed with the gcc exception, then yes, there might be a problem where anyone who distributes software compiled by EkoPath is obligated to license it under the GPLv3. That's pretty damn extreme, even for a free software project.
That's a huge, huge problem, if indeed it is the case. Because theoretically you wouldn't even be allowed to compile a BSD or MIT/X11 licensed software with this compiler, because you would violate the copyright license of the software you're compiling by trying to license it under the GPLv3. Would the same apply if you tried to compile LGPLed software?
This looks ugly. Unless I am really misunderstanding something here (such as, the gcc exception really is in effect for the entire compiler project and runtimes), we might have a situation where every program compiled by the PathScale EkoPath compiler either needs to be licensed under a license compatible with the GPLv3, or else you are not allowed to distribute it to anyone other than yourself and/or the company you work for. Wow.