[cfe-dev] clang-offload-bundler

[Jonas Hahnfeld via cfe-dev]

Hi Simone,

the same answers as always:
1. Offloading to GPUs is not yet working with Clang trunk.
2. Most of this has already been discussed on the mailing list or 
described in publications. In short, clang-offload-bundler should also 
use ELF sections for object files. And AFAIK, IBM XL uses the same 
mechanisms in most cases.

Jonas

Am 2018-01-11 19:15, schrieb Simone Atzeni via cfe-dev:
> Hi all,
> 
> I have been playing with the clang driver to see how it performs the
> compilations for an OpenMP program with target offloading (for NVidia
> GPU).
> 
> I noticed the use of the tool 'clang-offload-bundler' which seems to
> bundle together the object files for the host and for the device.
> In particular, if I use -c my foo.o will be a bundle of foo-x86_64.o
> and foo-cuda.o, and at link time it will unbundle the foo.o to obtain
> back the two object files.
> 
> Now, if I put my foo.o for example in a static library clang does not
> work because it does not know how to unbundle the object files from
> the library.
> 
> Other compilers, such as IBM XL create a specific section in the ELF
> to store the device code, in this way we always have one object file
> and there is no need to bundle/unbundle.
> Also if a object file/library was compiled with XL it can not be
> linked with clang and/or viceversa.
> 
> So, am I doing something wrong, or is this the status of the clang
> driver?
> Is the clang-offload-bundler the official choice to manage device
> code?
> If my analysis is correct, what's the workaround?
> 
> Thanks!
> Best,
> Simone
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