forked from OSchip/llvm-project
[AMDGPU] Correct gfx940 memory model documentation.
Differential Revision: https://reviews.llvm.org/D121397
This commit is contained in:
Stanislav Mekhanoshin
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2ebe971103
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3a37d08b35
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@ -8712,12 +8712,17 @@ For GFX940:
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work-group since they execute on the same CU. The exception is when in
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tgsplit execution mode as wavefronts of the same work-group can be in
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different CUs and so a ``buffer_inv sc0`` is required which will invalidate
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the L1 cache is in tgsplit mode.
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the L1 cache.
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* A ``buffer_inv sc1`` is required to invalidate the L1 cache for coherence
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* A ``buffer_inv sc0`` is required to invalidate the L1 cache for coherence
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between wavefronts executing in different work-groups as they may be
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executing on different CUs.
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* Atomic read-modify-write instructions implicitly bypass the L1 cache.
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Therefore, they do not use the sc0 bit for coherence and instead use it to
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indicate if the instruction returns the original value being updated. They
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do use sc1 to indicate system or agent scope coherence.
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* The scalar memory operations access a scalar L1 cache shared by all wavefronts
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on a group of CUs. The scalar and vector L1 caches are not coherent. However,
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scalar operations are used in a restricted way so do not impact the memory
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@ -8891,8 +8896,6 @@ in table :ref:`amdgpu-amdhsa-memory-model-code-sequences-gfx940-table`.
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- generic sc0=1 sc1=1
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store atomic monotonic - singlethread - global 1. buffer/global/flat_store
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- wavefront - generic
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store atomic monotonic - singlethread - global 1. buffer/global/flat_store
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- wavefront - generic
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store atomic monotonic - workgroup - global 1. buffer/global/flat_store
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- generic sc0=1
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store atomic monotonic - agent - global 1. buffer/global/flat_store
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@ -9639,7 +9642,7 @@ in table :ref:`amdgpu-amdhsa-memory-model-code-sequences-gfx940-table`.
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store that is being
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released.
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3. buffer/global/flat_store sc1=1
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3. buffer/global/flat_store sc1=1
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store atomic release - system - global 1. buffer_wbl2 sc0=1 sc1=1
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- generic
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- Must happen before
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@ -9694,7 +9697,7 @@ in table :ref:`amdgpu-amdhsa-memory-model-code-sequences-gfx940-table`.
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store that is being
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released.
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2. buffer/global/flat_store
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3. buffer/global/flat_store
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sc0=1 sc1=1
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atomicrmw release - singlethread - global 1. buffer/global/flat_atomic
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- wavefront - generic
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@ -10878,7 +10881,7 @@ in table :ref:`amdgpu-amdhsa-memory-model-code-sequences-gfx940-table`.
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------------------------------------------------------------------------------------
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load atomic seq_cst - singlethread - global *Same as corresponding
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- wavefront - local load atomic acquire,
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- generic except must generated
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- generic except must generate
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all instructions even
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for OpenCL.*
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load atomic seq_cst - workgroup - global 1. s_waitcnt lgkm/vmcnt(0)
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@ -10963,7 +10966,7 @@ in table :ref:`amdgpu-amdhsa-memory-model-code-sequences-gfx940-table`.
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instructions same as
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corresponding load
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atomic acquire,
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except must generated
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except must generate
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all instructions even
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for OpenCL.*
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load atomic seq_cst - workgroup - local *If TgSplit execution mode,
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@ -10972,7 +10975,7 @@ in table :ref:`amdgpu-amdhsa-memory-model-code-sequences-gfx940-table`.
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*Same as corresponding
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load atomic acquire,
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except must generated
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except must generate
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all instructions even
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for OpenCL.*
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@ -11066,22 +11069,22 @@ in table :ref:`amdgpu-amdhsa-memory-model-code-sequences-gfx940-table`.
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instructions same as
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corresponding load
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atomic acquire,
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except must generated
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except must generate
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all instructions even
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for OpenCL.*
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store atomic seq_cst - singlethread - global *Same as corresponding
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- wavefront - local store atomic release,
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- workgroup - generic except must generated
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- workgroup - generic except must generate
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- agent all instructions even
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- system for OpenCL.*
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atomicrmw seq_cst - singlethread - global *Same as corresponding
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- wavefront - local atomicrmw acq_rel,
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- workgroup - generic except must generated
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- workgroup - generic except must generate
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- agent all instructions even
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- system for OpenCL.*
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fence seq_cst - singlethread *none* *Same as corresponding
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- wavefront fence acq_rel,
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- workgroup except must generated
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- workgroup except must generate
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- agent all instructions even
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- system for OpenCL.*
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============ ============ ============== ========== ================================
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