[PATCH] D12414: [NVPTX] add an NVPTX-specific alias analysis

Tue Mar 15 11:23:04 PDT 2016

----- Original Message -----

> From: "Daniel Berlin" <dberlin at dberlin.org>
> To: reviews+D12414+public+cf5673a649e54709 at reviews.llvm.org
> Cc: "Jingyue Wu" <jingyue at google.com>, wengxt at gmail.com, "Chandler
> Carruth" <chandlerc at gmail.com>, "Justin Holewinski"
> <jholewinski at nvidia.com>, "Eli Bendersky" <eliben at google.com>, "Hal
> Finkel" <hfinkel at anl.gov>, "Bjarke Roune" <broune at google.com>, "Mark
> Heffernan" <meheff at google.com>, "llvm-commits"
> <llvm-commits at lists.llvm.org>
> Sent: Tuesday, March 15, 2016 1:03:35 PM
> Subject: Re: [PATCH] D12414: [NVPTX] add an NVPTX-specific alias
> analysis

> +1.

> If we need this, we should make it work ;)

> I'm not sure anyone sat down and said "it would be really bad to let
> targets have their own AA", and make such a decision
> (if they did, they didn't discuss it on llvm-dev)

I'm pretty sure I specifically requested that the infrastructure design not preclude this from working. We certainly don't want targets working around general AA deficiencies with target-specific passes, but for dealing with target-specific intrinsics and address spaces (etc.) I think it makes a lot of sense. 

-Hal 

> On Tue, Mar 15, 2016 at 10:57 AM, Hal Finkel < hfinkel at anl.gov >
> wrote:

> > hfinkel added a comment.
> 

> > In http://reviews.llvm.org/D12414#375657 , @jingyue wrote:
> 

> > > It doesn't work with the new alias analysis infrastructure.
> 
> > >
> 
> > > I didn't manage to find a way to run it with `opt`. The new
> > > AliasAnalysis needs to know and populate all potential alias
> > > analyses in a target-independent phase. However,
> > > NVPTXAliasAnalysis is target-dependent and not even visible to
> > > AliasAnalysis (e.g. compiling LLVM with NVPTX disabled).
> 

> > Do you have an alternative plan?
> 

> > It seems like we could add a feature in the new AA to query a
> > target-provided analysis.
> 

> > http://reviews.llvm.org/D12414
> 

-- 

Hal Finkel 
Assistant Computational Scientist 
Leadership Computing Facility 
Argonne National Laboratory 
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