[Bug middle-end/52173] internal compiler error: verify_ssa failed possibly caused by itm

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52173

--- Comment #11 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-09-20 15:08:55 UTC ---
(In reply to comment #10)
> On Wed, 19 Sep 2012, aldyh at gcc dot gnu.org wrote:
> 

> > After loop unrolling the above remains unchanged, but the following is inserted
> > *before* bb 3.  [Note, the following is after update_ssa(TODO_update_ssa), but
> > before cleanup_tree_cfg() for clarity.]
> > 
> >  <bb 8>:
> >   # .MEM_12 = PHI <.MEM_3(D)(2)>
> >   # ivtmp_5 = PHI <10(2)>
> >   # .MEM_6 = VDEF <.MEM_13>     <-- *************************** -->
> >                   ^^^^^^^^^^^^  <-- shouldn't this be <.MEM_12> ?????
> >                                 <-- *************************** -->
> 
> Yes.

Btw, is_new_name says yes to .MEM_12, false for .MEM_6 and 13.  update_ssa
should have adjusted the use .MEM_13 to .MEM_12, but it didn't for some
reason.

I see that the DEF stmt for .MEM_6 is

# .MEM_59 = VDEF <.MEM_13>
__transaction_relaxed  // SUBCODE=[ GTMA_HAVE_STORE ]

though before update_ssa.  That looks bogus to me.

Now I have to leave ... maybe the above is some hints to you (or I will
try to look further tomorrow).