[llvm] [AMDGPU][SIMemoryLegalizer] Ensure LDS -> DMA hazards respect fences (PR #220288)

[Krzysztof Drewniak via llvm-commits]

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@@ -8140,8 +8140,20 @@ in table :ref:`amdgpu-amdhsa-memory-model-code-sequences-gfx6-gfx9-table`.
                                                              is being released.
 
                                                          2. buffer/global/flat_atomic
-     fence        release      - singlethread *none*     *none*
+     fence        release      - singlethread *none*     1. s_waitcnt lgkmcnt(0)
                                - wavefront
+
+                                                           - Emit only on GFX9,
+                                                             before
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krzysz00 wrote:

... Ah, that's below, I misunderstood the "only" there

https://github.com/llvm/llvm-project/pull/220288