[LLVMdev] How to get debug dump of candidate pairs selected in BBVectorizer?

[Karthik Bhat]

On Thu, Apr 24, 2014 at 11:49 PM, Hal Finkel <hfinkel at anl.gov> wrote:

> ----- Original Message -----
> > From: "Karthik Bhat" <blitz.opensource at gmail.com>
> > To: llvmdev at cs.uiuc.edu
> > Sent: Thursday, April 24, 2014 6:23:15 AM
> > Subject: [LLVMdev] How to get debug dump of candidate pairs selected in
>       BBVectorizer?
> >
> >
> >
> > Hi All,
> > I'm trying to understand BB Vectorizer and gone through
> > http://llvm.org/devmtg/2012-04-12/Slides/Hal_Finkel.pdf
> >
> >
> > Wanted to know how to use bb-vectorize-debug-candidate-selection and
> > bb-vectorize-debug-pair-selection command arguments.
> >
> >
> > I tried the command with debug build clang -
> > clang -O2 test.c -mllvm -vectorize \
> > -mllvm -debug-only=bb-vectorize \
> > -mllvm -bb-vectorize-debug-pair-selection \
> > -mllvm -bb-vectorize-debug-candidate-selection as mentioned in
> > http://llvm.org/bugs/show_bug.cgi?id=11973 but it doesnt seem to
> > dump the candidate pair info as shown in bug id.
>
> A few things have changed since then. You'll need
> -vectorize-slp-aggressive instead of -vectorize.
>
> From clang, there are now direct flags:
> -fvectorize == loop vectorizer
> -fslp-vectorize == SLP vectorizer
> -fslp-vectorizer-aggressive == BB vectorizer
>
> Also, in case you don't know, most of the active upstream development has
> moved to the SLP vectorizer. The BB vectorizer still does a more expensive
> search, and I think it is mostly useful at this point for isolating useful
> cases that the SLP vectorizer misses.
>
> Thanks Hal for the info and heads-up. I have started to look into
SLPVectorizer and trying to understand the same.

>  -Hal
>
> >
> > Could someone help me out here with the command line argument to get
> > candidate pair selected info.
> > Thanks for the help! Regards Karthik Bhat
> > _______________________________________________
> > 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
>
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