[Bug tree-optimization/52560] if (r == -1) causes 'assuming signed overflow does not occur when simplifying conditional to constant'

[rjones at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52560

--- Comment #3 from Richard W.M. Jones <rjones at redhat dot com> 2012-03-12 
16:30:45 UTC ---
I see that this is actually a bug in our code.  I pushed
the following fix to libguestfs:
https://github.com/libguestfs/libguestfs/commit/d66dd2260c724bdfe57a8595aac37c8e9173cee5