[Bug target/104440] nvptx: FAIL: gcc.c-torture/execute/pr53465.c execution test

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104440

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #6)
> (In reply to Andrew Pinski from comment #5)
> > (In reply to Tom de Vries from comment #4)
> > > (In reply to Andrew Pinski from comment #2)
> > > > I thought there was another bug that reported a similar issue.
> > > 
> > > You mean related to nvptx, or in general?
> > 
> > It was in general. PR 21111 is related but not the same issue.
> > 
> > 
> > PR 61810 is the one pointing out the problems with init-regs and talking
> > about removing it.
> 
> I think there's a bug that ifcombine produces the situation and that
> valgrind complains about uninitialized uses.
> 
> Note that indeed the init-regs pass should go away.
> 
> It's somewhat unfeasible to compute a must-initialized regs so the issue
> is really hard to avoid.  But nobody tried yet (it would also come at a cost
> of course).  It would definitely inhibit all early short-circuiting on
> GENERIC (a good thing, but with a lot of fallout I think).
> 
> That said, --param logical-op-non-short-circuit=0 is only a workaround until
> you hit ifcombine doing similar transforms.
> 
> LOGICAL_OP_NON_SHORT_CIRCUIT is a target macro btw, so you could arrange it
> to be zero for nvptx (but that's of course too late since the hosts
> LOGICAL_OP_NON_SHORT_CIRCUIT value will be used).

But it would at least prevent ifcombine from doing the transform (ifcombine
only runs on the offload side).