[PATCH] D92483: AMDGPU - Use MUBUF instructions for global address space access

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec requested changes to this revision.
rampitec added a comment.
This revision now requires changes to proceed.

In D92483#2463314 <https://reviews.llvm.org/D92483#2463314>, @pvellien wrote:

> In D92483#2458755 <https://reviews.llvm.org/D92483#2458755>, @rampitec wrote:
>
>> But I still do not think this is a right thing to do to accept amdhsa on SI, even if you turn off flat instructions. SI does not support HSA.
>
> As far as I the support of HSA in SI processors.  Tony suggested that gfx60x processors should support AMDHSA OS because it is capable of supporting OpenCL  1.2 which not need generic pointers. This topic was discussed in amdgcn weekly and using MUBUF instructions for global address space in gfx60x is decided. The same is also documented in AMDGPU User Guide earlier.

But it is not. In fact AMDGPUUsage.rst says that SI does NOT support amdhsa and it is only supported starting from gfx700:

  **GCN GFX6 (Southern Islands (SI))** [AMD-GCN-GFX6]_
  -----------------------------------------------------------------------------------------------------------------------
  ``gfx600``  - ``tahiti``    ``amdgcn``   dGPU                    - Does not      - *pal-amdpal*
                                                                     support
                                                                     generic
                                                                     address
                                                                     space
  ``gfx601``  - ``pitcairn``  ``amdgcn``   dGPU                    - Does not      - *pal-amdpal*
              - ``verde``                                            support
                                                                     generic
                                                                     address
                                                                     space
  ``gfx602``  - ``hainan``    ``amdgcn``   dGPU                    - Does not      - *pal-amdpal*
              - ``oland``                                            support
                                                                     generic
                                                                     address
                                                                     space

It is only amdpal listed here.

What was discussed is that we can use buffer instructions for global on SI even if amdhsa is not supported.


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https://reviews.llvm.org/D92483