Re: [RFC][nvptx, libgomp] Add 128-bit atomic support

[Tom de Vries <tdevries@suse.de>]

On 9/2/20 1:48 PM, Tom de Vries wrote:
> On 9/2/20 12:44 PM, Jakub Jelinek wrote:
>> On Wed, Sep 02, 2020 at 12:22:28PM +0200, Tom de Vries wrote:
>>> And test-case passes on x86_64 with this patch (obviously, in
>>> combination with trigger patch above).
>>>
>>> Jakub, WDYT?
>>
>> I guess the normal answer would be use libatomic, but it isn't ported for
>> nvptx.
> 
> Ah, I was not aware of that one, filed
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96898 to look into that.
> 
>> I guess at least temporarily this is ok, though I'm wondering why
>> you need __sync_*_16 rather than __atomic_*_16, 
> 
> That's what omp-expand.c uses in expand_omp_atomic_pipeline:
> BUILT_IN_SYNC_VAL_COMPARE_AND_SWAP_N .
> 

I've got an updated version of this patch. It:
- no longer supplies the __atomic_load_16, since that's now handled by
  libatomic
- the __sync_val_compare_and_swap now uses __atomic_compare_and_swap,
  which also falls back on libatomic.

I'm currently retesting.

Any comments?

Otherwise, I'll commit on Monday.

Thanks,
- Tom