[Llvm-bgq-discuss] Details behind MPI wrapper for bgclang++

[Hal Finkel]

----- Original Message -----
> From: "Hal Finkel" <hfinkel at anl.gov>
> To: "Jack Poulson" <jack.poulson at gmail.com>
> Cc: llvm-bgq-discuss at lists.alcf.anl.gov
> Sent: Friday, March 1, 2013 3:39:31 PM
> Subject: Re: [Llvm-bgq-discuss] Details behind MPI wrapper for bgclang++
> 
> ----- Original Message -----
> > From: "Jack Poulson" <jack.poulson at gmail.com>
> > To: "Hal Finkel" <hfinkel at anl.gov>
> > Cc: "Jeff Hammond" <jhammond at alcf.anl.gov>,
> > llvm-bgq-discuss at lists.alcf.anl.gov
> > Sent: Friday, March 1, 2013 3:07:17 PM
> > Subject: Re: [Llvm-bgq-discuss] Details behind MPI wrapper for
> > bgclang++
> > 
> > On Fri, Mar 1, 2013 at 1:03 PM, Jack Poulson <
> > jack.poulson at gmail.com
> > > wrote:
> > 
> > 
> > 
> > 
> > On Fri, Mar 1, 2013 at 12:43 PM, Hal Finkel < hfinkel at anl.gov >
> > wrote:
> > 
> > 
> > 
> > 
> > The lightweight core files are really text files, I looked at the
> > line:
> > While executing instruction at..........0x000000000100c7c4
> > 
> > Then I ran powerpc64-bgq-linux-objdump -C -d Backproj-2d and looked
> > at the assembly around address 100c7c4 (if you search for it in the
> > file, note that objdump may omit the leading 0s in the address).
> > 
> > 
> > 
> > 
> > Thanks!
> > 
> > 
> > 
> > 
> > Can you try compiling/linking with
> > /home/projects/llvm/r175919-20130222/bin/bgclang++ instead of the
> > default one; this is a newer build and I'd like to see if it still
> > has whatever bug is yielding this miscompile.
> > 
> > 
> > Strangely enough, my executable ran correctly with the new version
> > of
> > LLVM (and passed my accuracy tests). I'm rerunning it again right
> > now to help rule out whether or not that was a fluke.
> > 
> > Any ideas as to what might have been the major change in the new
> > release?
> > 
> > 
> > 
> > Sigh. It was a fluke.
> 
> Hrmm... this being something that sometimes works is interesting. Are
> there any sources of non-determinism here? [I suppose that running
> on different partitions could cause PAMI to malloc memory
> differently; Jeff?]
> 
> > 
> > Perhaps we should take this offline to avoid spamming everyone else
> > on the list? I will try linking statically next.
> 
> Let's see if static linking "fixes" it; the list would certainly like
> to know that ;)

Jack, also please try compiling with these extra flags:
-mllvm -post-RA-scheduler=0
[if that fixes the problem I'll have a good idea of where the problem lies, and you'll have a work-around].

 -Hal

> 
>  -Hal
> 
> > 
> > Jack
> > 
> > 
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