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Mar 11, 2024
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[AMDGPU] Make generic versioning docs easier to find #84761

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28 changes: 17 additions & 11 deletions llvm/docs/AMDGPUUsage.rst
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Expand Up @@ -525,16 +525,7 @@ it supports. Such code objects may not perform as well as those for the non-gene

Generic processors are only available on code object V6 and above (see :ref:`amdgpu-elf-code-object`).

Generic processor code objects are versioned (see :ref:`amdgpu-elf-header-e_flags-table-v6-onwards`) between 1 and 255.
The version of non-generic code objects is always set to 0.

For a generic code object, adding a new supported processor may require the code generated for the generic target to be changed
so it can continue to execute on the previously supported processors as well as on the new one.
When this happens, the generic code object version number is incremented at the same time as the generic target is updated.

Each supported processor of a generic target is mapped to the version it was introduced in.
A generic code object can execute on a supported processor if the version of the code object being loaded is
greater than or equal to the version in which the processor was added to the generic target.
Generic processor code objects are versioned. See :ref:`amdgpu-generic-processor-versioning` for more information on how versioning works.

.. table:: AMDGPU Generic Processors
:name: amdgpu-generic-processor-table
Expand Down Expand Up @@ -621,6 +612,21 @@ greater than or equal to the version in which the processor was added to the gen
- ``gfx1151``
==================== ============== ================= ================== ================= =================================

.. _amdgpu-generic-processor-versioning:

Generic Processor Versioning
----------------------------

Generic processor (see :ref:`amdgpu-generic-processor-table`) code objects are versioned (see :ref:`amdgpu-elf-header-e_flags-table-v6-onwards`) between 1 and 255.
The version of non-generic code objects is always set to 0.

For a generic code object, adding a new supported processor may require the code generated for the generic target to be changed
so it can continue to execute on the previously supported processors as well as on the new one.
When this happens, the generic code object version number is incremented at the same time as the generic target is updated.

Each supported processor of a generic target is mapped to the version it was introduced in.
A generic code object can execute on a supported processor if the version of the code object being loaded is
greater than or equal to the version in which the processor was added to the generic target.

.. _amdgpu-target-features:

Expand Down Expand Up @@ -1803,7 +1809,7 @@ The AMDGPU backend uses the following ELF header:
mask. This is a value between 1 and 255,
stored in the most significant byte
of EFLAGS.
See :ref:`amdgpu-generic-processor-table`
See :ref:`amdgpu-generic-processor-versioning`
============================================ ========== =========================================

.. table:: AMDGPU ``EF_AMDGPU_MACH`` Values
Expand Down