llvm dev - Mar 2016 - Existing studies on the benefits of pointer analysis

On 21 March 2016 at 17:17, Daniel Berlin via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>>> Has anybody done any study in the past to evaluate what kinds of
features
>>> in pointer analyses will benefit what kinds of optimization passes?
>>
>> Yes.
>> Chris did many years ago, and i've done one more recently.
>>
>> Great! Are they published somewhere? Can the data be shared somehow?
>
> No, and sadly, no
This sounds like a good GSOC project.

Having the evaluation done is great, but if you can't share, than
that's pretty much useless to the community at large.

Even if a student does a less thorough evaluation, having something
out is better than having nothing, and with your expertise, I'm sure
we can get such a student doing some pretty capable analysis with
little resources.

cheers,
--renato

> On 21 March 2016 at 17:17, Daniel Berlin via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>>>> Has anybody done any study in the past to evaluate what kinds
of features
>>>> in pointer analyses will benefit what kinds of optimization
passes?
>>> Yes.
>>> Chris did many years ago, and i've done one more recently.
>>>
>>> Great! Are they published somewhere? Can the data be shared
somehow?
>> No, and sadly, no
> This sounds like a good GSOC project.
>
>
Need any volunteers?

I'd be interested in any work that relates to pointer analysis, 
including this as well as the " one to two years of work" Daniel 
mentioned. What held me back from submitting a proposal is the concern 
that such kind of explorative work whose outcome is not guaranteed to be 
useful may not be attractive enough to the LLVM devs.


-- 
Best Regards,

--
Jia Chen
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On Mon, Mar 21, 2016 at 10:40 AM, Renato Golin <renato.golin at
linaro.org>
wrote:
> On 21 March 2016 at 17:17, Daniel Berlin via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> >>> Has anybody done any study in the past to evaluate what kinds
of
> features
> >>> in pointer analyses will benefit what kinds of optimization
passes?
> >>
> >> Yes.
> >> Chris did many years ago, and i've done one more recently.
> >>
> >> Great! Are they published somewhere? Can the data be shared
somehow?
> >
> > No, and sadly, no
>
> This sounds like a good GSOC project.
>
> Having the evaluation done is great, but if you can't share, than
> that's pretty much useless to the community at large.
>
Which is why i've never mentioned it or used it in the community ;)

>
> Even if a student does a less thorough evaluation, having something
> out is better than having nothing, and with your expertise, I'm sure
> we can get such a student doing some pretty capable analysis with
> little resources.
>

FWIW, i'm not sure this is worthwhile at this time, because we pretty much
know enough of the low-hanging answers to keep someone busy with
implementation work for years.

(IE we know that scev-aa would be of significant benefit to PRE and GVN,
etc).

I would rather see someone spend their time getting SCEV-AA on by default
or CFL-AA on by default than doing another evaluation.
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On 21 March 2016 at 18:59, Daniel Berlin <dberlin at dberlin.org>
wrote:
> Which is why i've never mentioned it or used it in the community ;)
Makes sense. :)

> I would rather see someone spend their time getting SCEV-AA on by default
or
> CFL-AA on by default than doing another evaluation.
But those may not be simple enough for a GSOC, that's why I mentioned it.

The analysis could not only get us a birds view of the problem ahead,
but also introduce new developers to AA, which would make their future
work on SCEV-AA or CFL-AA easier. Kind of a teaching tool to get more
AA-savvy people.

cheers,
--renato