[Bug tree-optimization/56321] [4.8 Regression] ICE:segfault in midend for -funsafe-math-optimizations -O3

[wschmidt at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56321

--- Comment #10 from William J. Schmidt <wschmidt at gcc dot gnu.org> 2013-02-15 15:13:55 UTC ---
(In reply to comment #8)
> (In reply to comment #7)
> > I see.  The problem is a memory VUSE on the return statement that no longer has
> > a def.  The VDEF was associated with the __builtin_pow statement that was
> > expanded.  Looks like I need to release the SSA name.  Working on a fix.
> 
> Use unlink_stmt_vdef when removing a stmt that possibly has a VDEF.

Yes -- I've been trying that, but something more subtle seems to be going on. 
I think perhaps the statement isn't being removed but modified in place.  I've
been trying to unlink the VDEF when the call is known to go away later, and
that's not doing it either.  Going to have to get dirty with the debugger this
morning.