[cfe-dev] [NVPTX] Adjust data layout according to LLVM's change

[Denys Zariaiev via cfe-dev]

I didn't find any evidence that libdevice has anything related to i128's.
And seems, in general, i128 numbers are not very popular in CUDA
programming :)
Thanks for the advice!


On Wed, Jul 12, 2017 at 4:10 PM Hal Finkel <hfinkel at anl.gov> wrote:

>
> On 07/11/2017 03:21 PM, Denys Zariaiev via cfe-dev wrote:
>
> Hello,
>
> I'm curious, is it safe to change an alignment i128 type for NVPTX target?
> I made a patch to the LLVM backend <https://reviews.llvm.org/D34555> and
> added `-i128:128` into data layout.
>
> But after it became that LLVM and Clang layouts are different and error is
> thrown at Clang side:
> > backend data layout 'e-i64:64-i128:128-v16:16-v32:32-n16:32:64' does not
> match expected target description 'e-i64:64-v16:16-v32:32-n16:32:64'
>
> Could you please help with advice, can I just make another patch for Clang
> to modify the layout? Won't it break any backward compatibility?
>
>
> There could be some backward compatibility issues with linking new IR
> files with old IR files (because you're increasing the alignment
> requirements for i128), but often no more than other ISAs when new SIMD
> instructions are added, etc. For the NVPTX backend, this might be a concern
> if it affects anything in libdevice (the bitcode library that is shipped
> with CUDA in bitcode form), otherwise, I don't think it is a concern. In
> general, however, I think you should just update Clang.
>
>  -Hal
>
>
> Thanks a lot,
> Denys Zariaiev
>
>
> _______________________________________________
> cfe-dev mailing listcfe-dev at lists.llvm.orghttp://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>
>
> --
> Hal Finkel
> Lead, Compiler Technology and Programming Languages
> Leadership Computing Facility
> Argonne National Laboratory
>
>
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