On 9/17/21 10:24 AM, Tobias Burnus wrote:
> Hi Roger,
>
> some more generic remarks not specific to using new ISA features.
>
> On 17.09.21 00:53, Roger Sayle wrote:
>
>> Whilst there I also added -misa=sm_75 and -misa=sm_80 which are points
>> where other useful instructions were added to the ISA.
>
> First, my impression was that already sm_70 added lots of useful stuff,
> but granted sm_75 adds some more. In any case, the question is whether
> it makes sense to add those flags if no use is made of those flags.
>
> In particular, sm_80 is according to the following webpage only
> supported with PTX ISA 7.0 of CUDA 11.0. But GCC currently only supports
> -mptx=3.6 (default) and -mptx=6.3 (= CUDA 10).
> https://docs.nvidia.com/cuda/parallel-thread-execution/index.html#release-notes
>
I've dropped the sm_75 and sm_80 parts of the patch.
>
> Note that you missed to update gcc/config/nvptx/t-omp-device for the new
> sm_* and likewise the "-misa=@var{ISA-string}" section in
> gcc/gcc/doc/invoke.texi.
>
The support is currently not in a state that it can be advertised or
used at runtime, so I haven't included these changes.
Currently gcc doesn't build if the default is switched to sm_53 (
and mptx=6.3 as well), it runs into some internal errors in libgcc.
I've also tried to just run a float16 tests with target board
nvptx-none-run/-misa=sm_53/-mptx=6.3, but the
dg-require-effective-target float16 test doesn't succeed, again gcc runs
into internal errors.
But these are things that can be addressed later.
Committed.
Thanks,
- Tom
> Additionally, I wonder whether the preprocessor macros __nvptx__,
> __nvptx_softstack__, __nvptx_unisimt__ and __PTX_SM__ should be
> documented somewhere as well. As all but one are related to command-line
> options, I wonder whether the respective section in invoke.texi would be
> a good place for them.
>
> Tobias
>
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