Re: [pocl-devel] POCL Crash in vmovaps operation

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Hi Pekka,

thanks for your hints and the link. I had one buffer in the kernel call
that had a cast from a float type to a vector type. I have fixed this. But
the segfault remains. In the next few days I will try to cook up a simple
example that produces the segfault. Fortunately, the kernel itself is not
too complicated, so should be able to reduce it.

Best wishes

Timo

On Wed, 6 Mar 2019 at 10:20, Pekka Jääskeläinen (TAU) <
pek...@tu...> wrote:

> Yes, now that I look at it more closely,
> your stack trace looks _very_ much to the common data alignment
> issues people have. I think this might be worth a FAQ item somewhere.
>
>
> https://stackoverflow.com/questions/5983389/how-to-align-stack-at-32-byte-boundary-in-gcc
>
> On 6.3.2019 8.45, Pekka Jääskeläinen (TAU) wrote:
> > Hi Timo,
> >
> > Shooting in the dark here, but since just yesterday I debugged a similar
> > looking issue
> > which was caused by an illegal cast in the source code from float* to
> > float4*. It trusted
> > the alignment is still fine, which it wasn't after vectorization. A very
> > target specific programming
> > error which many ocl targets can easily hide.
> >
> > If this is something else, we need a test case, smaller the better, to
> > help you here.
> > Before opening an issue though, please with the latest master and LLVM 8.
> >
> > Pekka
> >
> > ------------------------------------------------------------------------
> > *From:* Timo Betcke <tim...@gm...>
> > *Sent:* Tuesday, March 5, 2019 11:27:12 PM
> > *To:* Portable Computing Language development discussion
> > *Subject:* [pocl-devel] POCL Crash in vmovaps operation
> > Dear Pocl community,
> >
> > I was just testing the newest Pocl Version (github master branch) with
> > our software. During execution of one of our kernels Pocl crashed.
> > Disassembling the crash shows the following operations during the crash:
> >
> > ------------------
> >     0x00007fffb81efdd8 <+664>:   vmulpd xmm2,xmm2,xmm6
> >     0x00007fffb81efddc <+668>:   vsubpd xmm2,xmm5,xmm2
> >     0x00007fffb81efde0 <+672>:   vpermilpd xmm5,xmm4,0x1
> >     0x00007fffb81efde6 <+678>:   vmulsd xmm3,xmm3,xmm5
> >     0x00007fffb81efdea <+682>:   vmulsd xmm4,xmm15,xmm4
> >     0x00007fffb81efdee <+686>:   vsubsd xmm3,xmm3,xmm4
> >     0x00007fffb81efdf2 <+690>:   vpermilpd xmm1,xmm1,0x1
> >     0x00007fffb81efdf8 <+696>:   vmulpd xmm0,xmm0,xmm1
> >     0x00007fffb81efdfc <+700>:   vpermilpd xmm1,xmm0,0x1
> >     0x00007fffb81efe02 <+706>:   vsubsd xmm0,xmm0,xmm1
> >     0x00007fffb81efe06 <+710>:   lea    rsi,[rdx+rdx*2]
> >     0x00007fffb81efe0a <+714>:   mov    rdx,QWORD PTR [rbx+0x38]
> > => 0x00007fffb81efe0e <+718>:   vmovaps XMMWORD PTR [rdx+rsi*8],xmm12
> > ---Type <return> to continue, or q <return> to quit---
> >     0x00007fffb81efe13 <+723>:   mov    QWORD PTR [rbx+0x40],rsi
> >     0x00007fffb81efe17 <+727>:   mov    QWORD PTR [rdx+rsi*8+0x10],0x0
> >     0x00007fffb81efe20 <+736>:   vinsertf32x4 ymm1,ymm16,xmm0,0x1
> > -----------------------------
> > This seems to be a similar bug that I discussed a year ago on the
> > mailing list. See the thread here:
> >
> https://www.mail-archive.com/poc...@li.../msg01087.html.
>
> > In summary, the issue was related to us using arrays of arrays within
> > our kernels and pocl creating wrong code for it.
> >
> > During that time a gist was suggested for Pocl, which I tested but did
> > not improve things. Afterwards I let it drop for a while as we were in
> > early development and had loads of building sites. But our software is
> > now close to release ready and it would be great to get it working with
> > pocl.
> >
> > Any help would be greatly appreciated.
> > Best wishes
> >
> > Timo
> >
> > --
> > Timo Betcke
> > Professor of Computational Mathematics
> > University College London
> > Department of Mathematics
> > E-Mail: t.b...@uc... <mailto:t.b...@uc...>
> > Tel.: +44 (0) 20-3108-4068
> >
> >
> > _______________________________________________
> > pocl-devel mailing list
> > poc...@li...
> > https://lists.sourceforge.net/lists/listinfo/pocl-devel
> >
>
> --
> Pekka
>
>
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>

-- 
Timo Betcke
Professor of Computational Mathematics
University College London
Department of Mathematics
E-Mail: t.b...@uc...
Tel.: +44 (0) 20-3108-4068