[Bug middle-end/68870] [6 Regression] ICE on valid code at -O1, -O2 and -O3 on x86_64-linux-gnu

[law at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68870

--- Comment #6 from Jeffrey A. Law <law at redhat dot com> ---
I'd say that changing genmatch (or any code) to know about the freelist is a
horrid hack and just papering over the problem.

I haven't put this case under a debugger, but presumably we've got a reference
to a released SSA_NAME in the IL, right?  Presumably in some code that isn't
trivially proved unreachable?