On Wed, Nov 21, 2018 at 6:48 AM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Tue, Nov 20, 2018 at 7:36 PM Andi Kleen <a...@firstfloor.org> wrote:
> >
> > On Tue, Nov 20, 2018 at 11:53:15AM +0100, Richard Biener wrote:
> > > On Fri, Nov 16, 2018 at 8:07 AM Uros Bizjak <ubiz...@gmail.com> wrote:
> > > >
> > > > On Fri, Nov 16, 2018 at 4:57 AM Andi Kleen <a...@firstfloor.org> wrote:
> > > > >
> > > > > From: Andi Kleen <a...@linux.intel.com>
> > > > >
> > > > > The earlier PTWRITE builtin definition was unnecessarily restrictive,
> > > > > only allowing register input to PTWRITE. The instruction actually
> > > > > supports memory operands too, so allow that too.
> > > > >
> > > > > gcc/:
> > > > >
> > > > > 2018-11-15  Andi Kleen  <a...@linux.intel.com>
> > > > >
> > > > >         * config/i386/i386.md: Allow memory operands to ptwrite.
> > > >
> > > > OK.
> > >
> > > Btw, I wonder why the ptwrite builtin is in SPECIAL_ARGS2
> > > commented as /* Add all special builtins with variable number of 
> > > operands. */?
> >
> > i think i put it in the same place as a similar builtin. AFAIK
> > those others don't have variable arguments either, so the comment
> > may be wrong?
>
> No idea...
>
> > >
> > > On the GIMPLE level this builtin also has quite some (bad) effects on
> > > alias analysis and any related optimization (vectorization, etc.).  I'll 
> > > have
> > > to see where the instrumenting pass now resides.
> >
> > It's fairly late now.
>
> OK, saw that.
>
> > Any suggestions for improvements? At some point I removed the edges
> > like the old MPX builtins to minimize memory usage, but that was
> > removed during an earlier review cycle.
>
> I guess it's fine now - it will have an effect on TER, limiting its ability
> a bit, but otherwise the builtin only lives up to RTL expansion where
> it becomes the UNSPEC_VOLATILE.  As said, instrumenting on
> RTL would be an improvement, I think HJ might be able to help with that.
>

What are the issues?

-- 
H.J.

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