SLP/Loop vectorizer pass ordering

[Chandler Carruth]

I've run our benchmarks and a sizable test suite. I see no regressions and
some small improvements. Please feel free to enable both features provided
everyone else is happy.


On Sun, Aug 31, 2014 at 9:50 PM, Hal Finkel <hfinkel at anl.gov> wrote:

> ----- Original Message -----
> > From: "Chandler Carruth" <chandlerc at google.com>
> > To: "James Molloy" <james at jamesmolloy.co.uk>
> > Cc: "Chad Rosier" <mcrosier at codeaurora.org>, "Hal Finkel" <
> hfinkel at anl.gov>, "LLVM Commits"
> > <llvm-commits at cs.uiuc.edu>, "Tobias Grosser" <tobias at grosser.es>
> > Sent: Wednesday, August 27, 2014 4:38:06 AM
> > Subject: Re: SLP/Loop vectorizer pass ordering
> >
> >
> >
> >
> >
> > On Wed, Aug 27, 2014 at 2:29 AM, James Molloy <
> > james at jamesmolloy.co.uk > wrote:
> >
> >
> >
> > Hi Chandler,
> >
> >
> > This is waiting on you reporting numbers, I think. Did you get a
> > chance to run your benchmarks?
> > Sorry, I should have followed up here as well as on IRC with Hal.
> >
> >
> > I tried to get numbers. However, enabling Hal's feature caused a
> > large number of my benchmarks to fail... over 50% of them. So I
> > didn't get much useful data. What I got looked fine, but I'd really
> > rather some higher confidence in the scoped-aa stuff first.
>
> Please try again after r216863 (which at least gives me a clean test-suite
> and self-host on Linux/x86_64). The noalias parameter attribute -> metadata
> conversion logic, as it turns out, was pretty broken -- it is certainly
> better now.
>
> In case you're curious where all your noalias parameters are coming from,
> aside from the obvious places where you have __restrict__, it is also that
> Clang adds noalias to every sret parameter (for aggregate return values).
> As a result, we actually get reasonable testing coverage from self-hosting
> on the noalias -> metadata conversion (or so I currently believe).
>
> >
> >
> > I'm not sure what to do next though. I mean, I can spend a bunch of
> > time trying to reduce a test case, but it will take me a huge amount
> > of time.
> >
> >
> > Note that all the code failing is compiled with no TBAA and there is
> > very little C code involved... so I feel lik ethere must be
> > something pretty basic that is going wrong with this new mode.
>
> Yes, there certainly was.
>
> Thanks again,
> Hal
>
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory
>
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