[LLVMdev] BasicAA unable to analyze recursive PHI nodes
Hal Finkel
hfinkel at anl.gov
Thu Jun 11 08:20:02 PDT 2015
----- Original Message -----
> From: "Tobias Edler von Koch" <tobias at codeaurora.org>
> To: "Daniel Berlin" <dberlin at dberlin.org>
> Cc: "LLVM Developers Mailing List" <llvmdev at cs.uiuc.edu>
> Sent: Thursday, June 11, 2015 10:02:37 AM
> Subject: Re: [LLVMdev] BasicAA unable to analyze recursive PHI nodes
>
> Hi Daniel,
>
> On Wed, 10 Jun 2015 17:11:02 -0700 Daniel Berlin
> <dberlin at dberlin.org>
> wrote:
>
> >
> > I didn't see numbers one way or the other. It probably has some
> > overhead, if it's the right solution, i'm sure it can be ade
> > faster.
>
> As far as I remember, scev-aa is off because of limitations in the
> current pass manager that would mean it would have to be recalculated
> far too often.
That's correct. It also may need some caching, or other performance-related work, to be sufficiently efficient to be on by default.
>
> >
> > > I think this is a common enough case for it to be
> > > handled by BasicAA.
> > >
> >
> > Can you provide some evidence?
> >
> > IE hard numbers of how often it occurs on some set of benchmarks or
> > something, and what the compile time cost is?
> >
> > It's really hard to say whether this is the right tradeoff without
> > any data.
>
> I agree. We're seeing about 3% improvement on a number of internal
> benchmarks, but I'll give this a try on SPEC etc. and share the
> results
> here (including compile time).
Sounds good; please do.
-Hal
>
> Thanks for your comments!
>
> Tobias
>
> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a
> Linux Foundation Collaborative Project.
> _______________________________________________
> 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
More information about the llvm-dev
mailing list