[LLVMdev] [cfe-dev][Openmp-dev] Provide LLVM IR and OpenMP LLVM IR as input in a Pass

Hal Finkel
Tue, 21 Oct 2014 21:02:51 -0000

----- Original Message -----
> From: "Simone Atzeni" <simone.at at gmail.com>
> To: "Hal Finkel" <hfinkel at anl.gov>
> Cc: llvmdev at cs.uiuc.edu, cfe-dev at cs.uiuc.edu, openmp-dev at
dcs-maillist2.engr.illinois.edu
> Sent: Tuesday, October 21, 2014 3:52:38 PM
> Subject: Re: [LLVMdev] [cfe-dev][Openmp-dev] Provide LLVM IR and OpenMP
LLVM IR as input in a Pass
>
>
> >> I want to use the pass Polly to find any data dependence in the
> >> code.
> >> Since it does not work on OpenMP,
> >
> > Why not? The loops in the outlined OpenMP regions are just regular
> > loops (with runtime bounds). Can polly not handle them?
>
> I tried it, it does not work and I also talked already with the Polly
> developers. They are slightly different, for example when the
> pragmas are translated actually the compiler introduces new
> functions and Polly get confused.

Right. So the long-term solution here is to figure out what enhancements are
necessary to the various components to make this work.

>
> >
> >> I was thinking to apply it on the
> >> not-OpenMP IR, then I need the results of Polly to apply other
> >> passes to the OpenMP IR.
> >
> > I don't think this will work for the OpenMP'd loops. The IR
will
> > look completely different, be in different functions, etc.
>
> What I did, and it works, is to build a script that call clang with
> Polly the first time and write the results in a file, then call
> Clang again with OpenMP and at the point I can apply other passes on
> the OpenMP IR reading the Polly results from that file.
> But it’s kind of a “dirty" solution, I was wondering if I can, in
> some way, introduce my own option "-myoption” that compile the code
> in both ways and make it available to the passes I want to call.

Not currently.

 -Hal

>
> Simone

--
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory