Re: [PATCH] PR target/70155: Use SSE for TImode load/store

[Jeff Law <law at redhat dot com>]

On 04/26/2016 03:17 AM, Richard Biener wrote:
> On Mon, 25 Apr 2016, Uros Bizjak wrote:
>
> > On Mon, Apr 25, 2016 at 4:47 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> > > On Mon, Apr 25, 2016 at 7:18 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
> > > > On Mon, Apr 25, 2016 at 2:51 PM, H.J. Lu <hongjiu.lu@intel.com> wrote:
> > > > > Tested on Linux/x86-64.  OK for trunk?
> > > >
> > > > > +  /* FIXME: Since the CSE pass may change dominance info, which isn't
> > > > > +     expected by the fwprop pass, call free_dominance_info to
> > > > > +     invalidate dominance info.  Otherwise, the fwprop pass may crash
> > > > > +     when dominance info is changed.  */
> > > > > +  if (TARGET_64BIT)
> > > > > +    free_dominance_info (CDI_DOMINATORS);
> > > > > +
> > > >
> > > > Please resolve the above problem first, target-dependent sources are
> > > > not the place to apply band-aids for middle-end problems. The thread
> > > > with the proposed fix died in [1].
> > > >
> > > > [1] https://gcc.gnu.org/ml/gcc/2016-03/msg00143.html
> > >
> > > free_dominance_info (CDI_DOMINATORS) has been called in other
> > > places to avoid this middle-end issue.   I don't know when the middle-end
> > > will be fixed.  I don't think this target optimization should be penalized by
> > > the middle-end issue.
> >
> > Let's ask Richard if he is OK with the workaround...
>
> Well, it's ultimately your call (it's a workaround in the target).
>
> Of course I'd like to see the underlying issue fixed and the
> workarounds in "other places" be removed.
Agreed.  It's fundamentally papering over a problem elsewhere.

jeff