llvm dev - May 2017 - [OpenCL][AMDGPU] Using AMDGPU generated kernel code for OpenCL

Hello everyone

I was wondering, what the correct way of using an AMDGPU generated kernel
code for OpenCL was. I am trying to provide Polly's GPGPU Code generation
with the ability to run on different GPU devices, such as AMD GPUs.

For NVIDIA, I simply retrieve a pre-compiled PTX string from the NVPTX
backend and pass that to OpenCL's 'clCreateProgramWithBinary'
function.
However, when doing the same with the AMDGPU backend and its returned
kernel string, OpenCL complains about an invalid binary.
This has been tried with a number of different target triples (eg.
'amdgcn--', 'amdgcn-amd-amdhsa' etc), and my assumption so far
is, that I
am not trying the correct Triple.
Or am I missing something entirely, and there have to be additional steps,
to get the correct ELF binary?

Thank you in advance for any help and pointers!

Best,
Philipp
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20170508/b9910505/attachment.html>

The binary format expected by AMD OpenCL drivers are elf-linked binaries. See

http://openwall.info/wiki/john/development/AMD-IL
https://community.amd.com/thread/166955

Michael


2017-05-08 11:43 GMT+02:00 Philipp Schaad via llvm-dev
<llvm-dev at lists.llvm.org>:
> Hello everyone
>
> I was wondering, what the correct way of using an AMDGPU generated kernel
> code for OpenCL was. I am trying to provide Polly's GPGPU Code
generation
> with the ability to run on different GPU devices, such as AMD GPUs.
>
> For NVIDIA, I simply retrieve a pre-compiled PTX string from the NVPTX
> backend and pass that to OpenCL's 'clCreateProgramWithBinary'
function.
> However, when doing the same with the AMDGPU backend and its returned
kernel
> string, OpenCL complains about an invalid binary.
> This has been tried with a number of different target triples (eg.
> 'amdgcn--', 'amdgcn-amd-amdhsa' etc), and my assumption so
far is, that I am
> not trying the correct Triple.
> Or am I missing something entirely, and there have to be additional steps,
> to get the correct ELF binary?
>
> Thank you in advance for any help and pointers!
>
> Best,
> Philipp
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>

Hi Michael

Thank you for those two links.
So if I understand that correctly, this means that the ISA generated by the
AMDGPU backend is only a part of the expected elf-linked binary file, and
would have to be correctly wrapped/packed up in order for OpenCL to accept
it?

Best,
Philipp

On Tue, 9 May 2017 at 15:49 Michael Kruse <llvmdev at meinersbur.de>
wrote:
> The binary format expected by AMD OpenCL drivers are elf-linked binaries.
> See
>
> http://openwall.info/wiki/john/development/AMD-IL
> https://community.amd.com/thread/166955
>
> Michael
>
>
> 2017-05-08 11:43 GMT+02:00 Philipp Schaad via llvm-dev
> <llvm-dev at lists.llvm.org>:
> > Hello everyone
> >
> > I was wondering, what the correct way of using an AMDGPU generated
kernel
> > code for OpenCL was. I am trying to provide Polly's GPGPU Code
generation
> > with the ability to run on different GPU devices, such as AMD GPUs.
> >
> > For NVIDIA, I simply retrieve a pre-compiled PTX string from the NVPTX
> > backend and pass that to OpenCL's
'clCreateProgramWithBinary' function.
> > However, when doing the same with the AMDGPU backend and its returned
> kernel
> > string, OpenCL complains about an invalid binary.
> > This has been tried with a number of different target triples (eg.
> > 'amdgcn--', 'amdgcn-amd-amdhsa' etc), and my
assumption so far is, that
> I am
> > not trying the correct Triple.
> > Or am I missing something entirely, and there have to be additional
> steps,
> > to get the correct ELF binary?
> >
> > Thank you in advance for any help and pointers!
> >
> > Best,
> > Philipp
> >
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20170510/c0bbbc00/attachment.html>