llvm dev - Oct 2013 - [LLVMdev] Contribute a new precise pointer analysis to LLVM

Hi Evan,

We did an experiment using the LLVM test suite: we compare the
overhead of using our analysis to the LLVM default, both with -O2
option.

The overall overhead of compiling the whole test suite using our
analysis is 36.5%.
The biggest overhead is  observed in
"SingleSource/Benchmarks/Misc/flops-5", where we are 5 times slower:
0.07s (with our analysis) compared to 0.0133s(default).
This may not be accurate as the compilation time in both cases are quite small.

Remind that the compilation time is reported by running our analysis
over individual files, the compilation time overhead will be larger if
we link all individual compilation units together and run the
analysis over the whole application.

Regards,
Lian

On Sat, Oct 19, 2013 at 7:56 AM, Evan Cheng <evan.cheng at apple.com>
wrote:
>
> On Oct 17, 2013, at 10:51 PM, lian li <lianli at gmail.com> wrote:
>
>> Thanks, Chris.
>>
>> We are interested in contributing it to LLVM itself. Our manager
>> agrees to commit resources for maintenance needs if it is accepted by
>> the community.
>
> This is great. Please make sure Oracle legal sign off on explicitly
granting LLVM the use of the patents associated with the work.
>
> On the compile time front, can you do a comparison with the LLVM default
and your new AA? You can just build the LLVM test suite.
>
> Thanks,
>
> Evan
>
>>
>> Regards,
>> Lian
>>
>> On Fri, Oct 18, 2013 at 3:43 PM, Chris Lattner <clattner at
apple.com> wrote:
>>>
>>> On Oct 17, 2013, at 5:20 PM, lian li <lianli at gmail.com>
wrote:
>>>
>>> Hi All,
>>>
>>> This is Lian Li  from Oracle Labs in Brisbane Australia.
>>>
>>> We have developed a precise and highly efficient pointer analysis
>>> framework on top of LLVM,  The approach is flow, context, and field
>>> sensitive, details are described in the two papers below:
>>>
>>> "Boosting the performance of flow-sensitive points-to analysis
using
>>> value flow" (in ESEC-FSE 2011), and
>>> "Precise and scalable context-sensitive pointer analysis via
value
>>> flow graph" (in ISMM 2013).
>>>
>>> The analysis was initially developed for the purpose of bug
checking,
>>> and is now extended to support compiler optimizations. We have
tested
>>> it with existing compiler optimizations in LLVM, and have seen
>>> promising results.
>>>
>>> We are now considering to make this analysis available to the LLVM
>>> community, and contribute resources for future maintenance needs,
>>> provided that there is enough interest. We think that a new precise
>>> pointer analysis in LLVM can enable more new optimization and
analysis
>>> techniques to be developed in LLVM.
>>>
>>> Any people interested in seeing a new precise pointer analysis in
LLVM?
>>>
>>>
>>> This sounds very interesting.  Even if it isn't fast enough to
be used with
>>> (for example) clang -O2 or -O3, having such a precise analysis
would be a
>>> great baseline for doing other alias analysis work.
>>>
>>> Are you interested in contributing this to LLVM itself, or just
asking if
>>> people would be interested to see the code in some other form?
>>>
>>> -Chris
>>
>>
>>
>> --
>> // Copyright @ 2011 Authorized by ** LIAN LI **
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>


-- 
// Copyright @ 2011 Authorized by ** LIAN LI **

----- Original Message -----
> Hi Evan,
> 
> We did an experiment using the LLVM test suite: we compare the
> overhead of using our analysis to the LLVM default, both with -O2
> option.
It might also be interesting to try with -O3; I don't know if we have any
significant vectorizable loops in the test suite with a large number of arrays,
but if we do, this kind of analysis should help.
> 
> The overall overhead of compiling the whole test suite using our
> analysis is 36.5%.
Maybe a good candidate for -fexpensive-optimizations? (or -O4?)
> The biggest overhead is  observed in
> "SingleSource/Benchmarks/Misc/flops-5", where we are 5 times
slower:
> 0.07s (with our analysis) compared to 0.0133s(default).
> This may not be accurate as the compilation time in both cases are
> quite small.
In my experience, compile-time measurements from a normal test-suite
configuration less than 0.1s are too noisy to use.
> 
> Remind that the compilation time is reported by running our analysis
> over individual files, the compilation time overhead will be larger
> if
> we link all individual compilation units together and run the
> analysis over the whole application.
Yes, LTO tests would be interesting too.

Thanks again,
Hal
> 
> Regards,
> Lian
> 
> On Sat, Oct 19, 2013 at 7:56 AM, Evan Cheng <evan.cheng at apple.com>
> wrote:
> >
> > On Oct 17, 2013, at 10:51 PM, lian li <lianli at gmail.com>
wrote:
> >
> >> Thanks, Chris.
> >>
> >> We are interested in contributing it to LLVM itself. Our manager
> >> agrees to commit resources for maintenance needs if it is accepted
> >> by
> >> the community.
> >
> > This is great. Please make sure Oracle legal sign off on explicitly
> > granting LLVM the use of the patents associated with the work.
> >
> > On the compile time front, can you do a comparison with the LLVM
> > default and your new AA? You can just build the LLVM test suite.
> >
> > Thanks,
> >
> > Evan
> >
> >>
> >> Regards,
> >> Lian
> >>
> >> On Fri, Oct 18, 2013 at 3:43 PM, Chris Lattner
> >> <clattner at apple.com> wrote:
> >>>
> >>> On Oct 17, 2013, at 5:20 PM, lian li <lianli at
gmail.com> wrote:
> >>>
> >>> Hi All,
> >>>
> >>> This is Lian Li  from Oracle Labs in Brisbane Australia.
> >>>
> >>> We have developed a precise and highly efficient pointer
analysis
> >>> framework on top of LLVM,  The approach is flow, context, and
> >>> field
> >>> sensitive, details are described in the two papers below:
> >>>
> >>> "Boosting the performance of flow-sensitive points-to
analysis
> >>> using
> >>> value flow" (in ESEC-FSE 2011), and
> >>> "Precise and scalable context-sensitive pointer analysis
via
> >>> value
> >>> flow graph" (in ISMM 2013).
> >>>
> >>> The analysis was initially developed for the purpose of bug
> >>> checking,
> >>> and is now extended to support compiler optimizations. We have
> >>> tested
> >>> it with existing compiler optimizations in LLVM, and have seen
> >>> promising results.
> >>>
> >>> We are now considering to make this analysis available to the
> >>> LLVM
> >>> community, and contribute resources for future maintenance
needs,
> >>> provided that there is enough interest. We think that a new
> >>> precise
> >>> pointer analysis in LLVM can enable more new optimization and
> >>> analysis
> >>> techniques to be developed in LLVM.
> >>>
> >>> Any people interested in seeing a new precise pointer analysis
in
> >>> LLVM?
> >>>
> >>>
> >>> This sounds very interesting.  Even if it isn't fast
enough to be
> >>> used with
> >>> (for example) clang -O2 or -O3, having such a precise analysis
> >>> would be a
> >>> great baseline for doing other alias analysis work.
> >>>
> >>> Are you interested in contributing this to LLVM itself, or
just
> >>> asking if
> >>> people would be interested to see the code in some other form?
> >>>
> >>> -Chris
> >>
> >>
> >>
> >> --
> >> // Copyright @ 2011 Authorized by ** LIAN LI **
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
> 
> 
> 
> --
> // Copyright @ 2011 Authorized by ** LIAN LI **
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> 
-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory

On Tue, Oct 22, 2013 at 9:55 AM, Hal Finkel <hfinkel at anl.gov> wrote:
> ----- Original Message -----
> > Hi Evan,
> >
> > We did an experiment using the LLVM test suite: we compare the
> > overhead of using our analysis to the LLVM default, both with -O2
> > option.
>
> It might also be interesting to try with -O3; I don't know if we have
any
> significant vectorizable loops in the test suite with a large number of
> arrays, but if we do, this kind of analysis should help.
>
We perform loop vectorization at -O2 now?

>
> >
> > The overall overhead of compiling the whole test suite using our
> > analysis is 36.5%.
>
> Maybe a good candidate for -fexpensive-optimizations? (or -O4?)
>
It would also be helpful to know what the execution performance impact is
to provide context.

>
> > The biggest overhead is  observed in
> > "SingleSource/Benchmarks/Misc/flops-5", where we are 5 times
slower:
> > 0.07s (with our analysis) compared to 0.0133s(default).
> > This may not be accurate as the compilation time in both cases are
> > quite small.
>
> In my experience, compile-time measurements from a normal test-suite
> configuration less than 0.1s are too noisy to use.
>
> >
> > Remind that the compilation time is reported by running our analysis
> > over individual files, the compilation time overhead will be larger
> > if
> > we link all individual compilation units together and run the
> > analysis over the whole application.
>
> Yes, LTO tests would be interesting too.
>
> Thanks again,
> Hal
>
> >
> > Regards,
> > Lian
> >
> > On Sat, Oct 19, 2013 at 7:56 AM, Evan Cheng <evan.cheng at
apple.com>
> > wrote:
> > >
> > > On Oct 17, 2013, at 10:51 PM, lian li <lianli at gmail.com>
wrote:
> > >
> > >> Thanks, Chris.
> > >>
> > >> We are interested in contributing it to LLVM itself. Our
manager
> > >> agrees to commit resources for maintenance needs if it is
accepted
> > >> by
> > >> the community.
> > >
> > > This is great. Please make sure Oracle legal sign off on
explicitly
> > > granting LLVM the use of the patents associated with the work.
> > >
> > > On the compile time front, can you do a comparison with the LLVM
> > > default and your new AA? You can just build the LLVM test suite.
> > >
> > > Thanks,
> > >
> > > Evan
> > >
> > >>
> > >> Regards,
> > >> Lian
> > >>
> > >> On Fri, Oct 18, 2013 at 3:43 PM, Chris Lattner
> > >> <clattner at apple.com> wrote:
> > >>>
> > >>> On Oct 17, 2013, at 5:20 PM, lian li <lianli at
gmail.com> wrote:
> > >>>
> > >>> Hi All,
> > >>>
> > >>> This is Lian Li  from Oracle Labs in Brisbane Australia.
> > >>>
> > >>> We have developed a precise and highly efficient pointer
analysis
> > >>> framework on top of LLVM,  The approach is flow, context,
and
> > >>> field
> > >>> sensitive, details are described in the two papers below:
> > >>>
> > >>> "Boosting the performance of flow-sensitive
points-to analysis
> > >>> using
> > >>> value flow" (in ESEC-FSE 2011), and
> > >>> "Precise and scalable context-sensitive pointer
analysis via
> > >>> value
> > >>> flow graph" (in ISMM 2013).
> > >>>
> > >>> The analysis was initially developed for the purpose of
bug
> > >>> checking,
> > >>> and is now extended to support compiler optimizations. We
have
> > >>> tested
> > >>> it with existing compiler optimizations in LLVM, and have
seen
> > >>> promising results.
> > >>>
> > >>> We are now considering to make this analysis available to
the
> > >>> LLVM
> > >>> community, and contribute resources for future
maintenance needs,
> > >>> provided that there is enough interest. We think that a
new
> > >>> precise
> > >>> pointer analysis in LLVM can enable more new optimization
and
> > >>> analysis
> > >>> techniques to be developed in LLVM.
> > >>>
> > >>> Any people interested in seeing a new precise pointer
analysis in
> > >>> LLVM?
> > >>>
> > >>>
> > >>> This sounds very interesting.  Even if it isn't fast
enough to be
> > >>> used with
> > >>> (for example) clang -O2 or -O3, having such a precise
analysis
> > >>> would be a
> > >>> great baseline for doing other alias analysis work.
> > >>>
> > >>> Are you interested in contributing this to LLVM itself,
or just
> > >>> asking if
> > >>> people would be interested to see the code in some other
form?
> > >>>
> > >>> -Chris
> > >>
> > >>
> > >>
> > >> --
> > >> // Copyright @ 2011 Authorized by ** LIAN LI **
> > >> _______________________________________________
> > >> LLVM Developers mailing list
> > >> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> > >
> >
> >
> >
> > --
> > // Copyright @ 2011 Authorized by ** LIAN LI **
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
>
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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